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14. TROUBLESHOOTING GUIDE
14. FEHLERSUCHE
14. RECHERCHES DE PANNES
14. GUIA PARA LA LOCALIZACION DE FALLAS
14. TROUBLESHOOTING GUIDE
Be sure to check the following before calling an authorized service station.
¡
Turn off the power switch and disconnect the power cord before carrying out troubleshooting.
The motor will keep turning even after the power is switched off as a result of the motor's inertia. Wait
until the motor stops fully before starting work. The machine may operate if the treadle is pressed by mistake,
which could result in injury.
Problem
1. Sewing machine pulley
doesn't turn.
2. Needle thread and bobbin
thread break.
3. Seams don't match.
From the library of: Superior Sewing Machine & Supply LLC
CAUTION
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Is a breaker or fuse blown?
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Is the power cord disconnected?
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Is the V-belt installed?
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Is the needle tip bent? Is the needle tip blunt?
If the needle tip is bent or broken, replace the needle.
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Is the needle properly installed?
If it is incorrect, install the needle correctly.
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Is the machine properly threaded?
If it is incorrect, thread the thread correctly.
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Is the rotary hook properly lubricated?
If the oil level is below the lower reference line in the oil sight glass,
add more oil.
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Is dust or thread in the rotary hook?
Clean the rotary hook.
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Is the upper thread tension too strong or too weak?
Adjust the upper thread tension.
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Is the rotary hook, feed dog or other part damaged?
If they are damaged, smooth them with an oiled grindstone or re-
place the damaged parts.
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Is the presser foot pressure too weak?
Adjust the presser foot pressure.
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Is the feed dog too low?
Adjust the feed dog height.
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Is the bobbin scratched?
If the bobbin is damaged, smooth it with an oiled grindstone or re-
place it.
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Is the V-belt tension too low?
Adjust so that there is 10–14 mm of deflection in the V-belt when it
is pushed with a finger.
– 75 –
Where to check
Page
16
22
22
30
46
46
38
38
48
16
TN-8400, 8700 (English)
TL-8400 (English)
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