By Ron Anderson,
A-1 Sewing Machines Repair Specialists
(edited by Mindconnection)
Has a customer ever asked, "Why should I pay someone to clean and oil my machine,
when I can do it my self?"
The answer to that customers questions is simple. There is far more to proper
maintenance than just cleaning the shuttle area and putting a few drops of oil here and
there. This is especially true on todays sophisticated machines. In fact, I would be
willing to bet that the majority of users could not even get the covers off many of the
I cant tell you how many
times Ive had a customer insist her machine doesnt need cleaning because she
does it herself often. The expressions on their faces are priceless when I remove the
covers and show them just how much fuzz and gunk is really in there. So much for "I
did it myself."
The thousands of makes and models make
it virtually impossible to detail all the particular maintenance requirements of each and
every machine. However, if you have a question about a specific model, please write to me and maybe we'll answer it in a future
I like to start with the repair tag or work order. Look at the customers
complaint. Why did the customer bring the machine to you? Is it skipping stitches? Poor
tension? Does it break needles or thread? Does it sound like it has indigestion? Such
information gives you an idea of what to look for, but dont limit the inspection to
just the complaint. Many things can be at the root of specific problems.
1. Remove the needle. Is it obviously bent? Is it dull or burred?
2. Turn the machine over by hand and check for binding. Does it move
easily and freely? Does the hook or shuttle move? If you sense it is binding, determine
why. Is there an accumulation of old oil, grease, or dirt? Check the belt: is it too
tight? Check behind the hand wheel and motor pulley: Is thread wound around the shaft? If
the hook or shuttle didnt move, check the gears and or timing belt. If it is an
oscillating shuttle, check the connecting link. Is it loose or broken?
3. If you experienced no binding and the hook or shuttle is moving,
install a new needle and turn the machine by hand again. Is the needle hitting? If so,
check the needle bar height and hook timing and needle clearance. Are they to the
specifications in the repair manual? Check for broken and/or burred hook points. This is
also a good time to check the thread guards and/or race cap and shuttle driver spring.
Dont forget those position brackets.
4. If you can turn the machine by hand without causing damage, plug it
in and run it. Or remove the needle and run it. Does it actually run? Are there any
unusual noises? Is the speed correct? If you hear a noise out of the norm or the speed
seems incorrect, then find out why.
If a Machine Doesnt Run
If the machine doesn't run, I start with the cord. If the machine is an older style
with an AC motor, you can use jumper leads to "hot wire" it. If this
causes the machine to run, youve eliminated a motor problem, and can now focus on
the cord and foot control.
Caution do not "hot wire" a machine with a DC type motor or an
electronic speed control. You will damage these parts beyond repair.
If it doesnt run by hot-wiring it, connect your leads directly to the motor
wires. If it still doesnt run, then the problem is in the motor. Check the brushes.
If they appear to be good, then replace the motor. If the machine does run by connecting
leads directly to the motor, check the switch (if it has one) with a meter. If there is no
switch, check the connections in the terminal block.
If the machine is electronic or uses a DC motor, start swapping parts with known good
ones to find the source of the problem. The same goes with the lead and foot control.
Although you can use your meter to narrow the problem down to either the foot control or
the cord, most machines will have a manual for troubleshooting problems. Use the book!
If the machine runs too slowly, start with the foot control: attach a new one. If the
result is proper speed and range, you know it is the controller. If the result is still
slow, check the belt. Is it too tight or too loose? If the belt seems satisfactory, check
again for binding in the machine; then try replacing the motor.
Listen to the Machine
Unusual noises can be as simple as poor lubrication or as complex as loose or worn
parts. Many times, a trained ear is all it takes to find and eliminate a noise. Other
times, you can spend a great deal of time finding the source. Start by listening closely.
Is it knocking, grinding, squeaking or squealing? Locate the source of the noise check for
excessive wear. If it is not readily apparent where the noise is coming from, place a
screwdriver between suspect parts and your ear.
Note: do not put a screwdriver on your ear and a moving part! Place it
adjacent to the part on a stationary portion of the machine. Youll hear the noise
transmitted through the case.
Remove the Covers
If you havent already removed the covers and the needle and slide plates, do so.
Check the needle plate. Is it bent, burred, broken? Is the hole enlarged from previous
repair or damage?
Many times, you can straighten a needle plate with a few light taps of a hammer. If the
hole has burring from repeated hitting of the needle, you may be able to smooth it with a
file or polish it with emery cloth. Be careful not to remove too much and make the hole
too large. Doing so can cause flagging resulting in skipped stitches.
Visually inspect all the parts in the machine for looseness or wear. Check to see
nothing is bent, cracked or broken. Cracked or broken parts are usually obvious; bent
parts can be difficult to spot. Often, bent parts are those that protrude from the machine
surfaces. These include take-up levers, bobbin winders, presser bar lifters, tension
assemblies, thread guides, stitch length levers and various control devices. Ive
encountered bent needle and presser bars, assorted driving shafts, connecting links, and
screws. Sometimes you can straighten bent parts, but the reduction in strength usually
Other things to check
Feed dog height and timing.
The feed dogs should rise above the needle plate approximately 1mm. With the stitch length
set to the longest stitch, they should have traveled their full distance and be just below
the needle plate when the point of the needle has reaches the top of the needle plate on
its downward stroke.
Pendulum timing (zigzag machines).
The needle must not start its left or right movement until the point of the needle rises
above the thickest layer of fabric being sewn, approx. 5/32 of an inch.
Reverse cycle stitches (stretch stitch).
To test, place a piece of paper under the presser foot and turn the machine over by hand
in the operating direction through a complete cycle of stitches, two forward and one back.
The point of the needle must penetrate the paper on the reverse stitch in the exact same
hole as the previous forward stitch. If it doesnt, adjust it.
Button Hole stitch.
Are the forward and reverse stitches of equal length? Is the distance between the left and
right rows of stitches properly spaced? If not adjust the machine.
On computerized machines.
Do all of the stitch functions perform properly? Try them all; sometimes a problem with a
board will affect only one type of stitch or function.
Presser bar height and pressure.
Adjust the presser bar so the fabric feeds without slipping or pushing. The pressure
usually is user-adjustable, but if the presser bar is to high or to low this adjustment
may not work. Consult the service manual for specific requirements. Usually when the feed
dogs are at their lowest point, the presser foot should contact the needle plate and exert
enough pressure to keep the thinnest of materials from shifting under the foot.
Is the needle central to the hole in the needle plate? Many machines come equipped with a
seam guide on the needle plate. Use a scale to measure the distance from the center of the
needle (the point ) to one of the measures on the plate. In case the plate has no scaling,
the needle should be either central in the hole, or in the case of left needle position
machines. The needle must penetrate the fabric in the exact same place when straight
stitching as it does on the left through of the zigzag stitch.
The machine must not, with the stitch length control set to zero, move the fabric being
sewn in any direction. If it does, adjust per the service manual.
Upper thread tension assembly and bobbin case.
Inspect for worn and broken parts during the initial inspection. Common problems include
excess lint and debris between the discs ( upper tension ) or the under the spring (bobbin
case); worn or broken check spring; grooved or rusted tension discs or springs; missing or
These steps should provide you with ample information to properly estimate the cost of
repair on many machines. Some will require further analysis, some less. Determine as many
of the machines problems during your initial inspection as possible. This avoids the
unpleasant task of admitting to your customer that you missed something. Be thorough the
The maintenance tune-up may very well be the most important part of any repair job. It
is also the bread and butter of the service business and the part of the business upon
which our reputations usually depend.
1. If you havent already done so, remove as many of the covers as
practical: the top, bottom, and side covers always, as well as the needle and slide
plates. The object is to expose as much of the inside of the machine as possible.
2. Use compressed air (not the same as "canned air"), if you have it,
to blow out as much of the dust and lint as you can. You can also use a canister type
vacuum cleaner with the hose attached to the exhaust, and a crevice tool. Though much
slower, a small brush and some sort of pick can remove the dust and lint, too. Be sure to
get in all the nooks and crannies, i.e. between the feed dogs, under and around the hook,
in the shuttle raceway.
3. Check for thread wound around the mechanisms. Some common spots: take-up
links, under the hook or bobbin case basket, handwheel, motor pulleys. On machines with
rotary hooks, remove the gib screws and the bobbin case basket. Youll usually find
an accumulation of gunk in there.
4. Check for loose screws and connections, as well as gears not properly
meshing. I use a dental pick to get in between gear teeth and pick out the accumulated
grease and lint. This is especially important on newer machines with the fine tooth gears;
buildup can cause premature failure.
5. If the machine has a belt, adjust the tension. It should be tight enough to
prevent slipping, but not so tight that it causes the machine to slow down.
6. Lubricate the machine. One or two drops of clear white oil on all moving
parts (where metal parts contact with each other). Use grease on the gears and cams. I use
white lithium grease for this. It seems to hold up well and resists flying (coming off the
surface from centrifugal force).
7. Replace the covers.
8. Remove any burrs or damage from the needle plate and replace it and the slide
cover if necessary.
9. If you can, disassemble the tension assembly and clean between the disks.
Sometimes just blowing air through them wont get everything out.
10. Remove the spring on the bobbin case and clean under it.
11. Reassemble the bobbin case and tension assembly. Make preliminary tension
12. Wind a bobbin to ensure the bobbin winder works properly.
13. Insert a new needle, thread the machine and sew a little. Make final tension
adjustments. Ensure the check spring is functioning properly.
14. Sew a sample, include as many of the stitch functions as necessary to be
certain they all work properly. Use various widths and lengths; adjust any that perform
15. Use a mild detergent to clean the outside of the machine thoroughly.
16. Put it back in its case, or a plastic cover. Now youre ready
for delivery or to carry the machine to the customer's car when they come to pick up the
If anything you read here is contrary to the manufacturers recommendations as
specified in a service manual, defer to the manual.
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