Fix Thread Bunching Under Fabric on Baby Lock Sewing Machine
Diagnose and resolve thread bunching issues caused by lint or thread caught in the upper tension mechanism
Difficulty: Medium
Estimated time: 10 minutes
Step 1
Tools Needed
-
Canned air (optional) -
Phillips Screwdriver
-
Straight pin or needle
-
Tweezers
Check Initial Symptoms
Is the thread bunching or showing loose tension specifically on the bottom/underside of your fabric?
Tools Needed
-
Canned air (optional)
-
Phillips Screwdriver
-
Straight pin or needle
-
Tweezers
Access and Clean the Upper Tension Mechanism
We'll open the tension area to check for lint, fuzz, or thread that may be causing the problem, then test if it's resolved.
- Turn off the power switch on your machine.
- Locate the small cap covering the tension mechanism screw.
- Insert a straight pin or needle through the hole in the cap.
- Lift the cap up and away to expose the Phillips screw underneath.
- Using a Phillips screwdriver, remove the screw from the top.
- Lift the back of the tension cover gently and angle it up.
- Slide the cover off to the side to expose the automatic tension system.
- Rotate the tension mechanism counterclockwise to open the tension discs.
- Look for any threads, lint, or fuzz caught in the tension discs.
- If you see debris, remove it with tweezers or use short bursts of canned air (held upright) to clear the area.
- Check under the pre-tension plate for any trapped material.
- Position the cover back by angling the front notch into its opening.
- Let the back of the cover sit into place.
- Replace and tighten the Phillips screw from the top.
- Use the pin to help position the cap flat as you snap it back into place over the screw.
- Turn the power back on.
- Thread the machine with new thread following the proper path.
- Test sew on a scrap piece of fabric to check if the bunching is resolved.
Tools Needed
-
Canned air (optional)
-
Phillips Screwdriver
-
Straight pin or needle
-
Tweezers
Issue Resolved
Great! The cleaning resolved the thread bunching. Your machine should now maintain proper tension. Remember to have your machine serviced annually at your local Baby Lock retailer for optimal performance.
Tools Needed
-
Canned air (optional)
-
Phillips Screwdriver
-
Straight pin or needle
-
Tweezers
Check Additional Causes
Since cleaning the upper tension didn't resolve the issue, are you using the correct needle size and type for your fabric, and is the bobbin properly inserted?
Tools Needed
-
Canned air (optional)
-
Phillips Screwdriver
-
Straight pin or needle
-
Tweezers
Professional Service Needed
The tension mechanism may need professional adjustment or there may be a timing issue. Take your machine to your local Baby Lock retailer for service, as they recommend annual maintenance.
Tools Needed
-
Canned air (optional)
-
Phillips Screwdriver
-
Straight pin or needle
-
Tweezers
Check Basic Setup First
Before servicing the tension mechanism, verify your needle is the correct size for your fabric, isn't bent or dull, and that your bobbin is properly inserted with thread pulling in the correct direction. If these basics are correct, return to this guide. Otherwise, correct them first and test again.