What Are The Serger Lower Looper Problems?
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What Are The Serger Lower Looper Problems?

Recently updated on August 6th, 2022

If your serger acts up during a sewing project, it can be very frustrating and hard to pinpoint the problem. It is more likely than not the lower looper of the serger that is the culprit; this part loops the thread at the stitching line and at the edge of the fabric under the stitching line.

The purpose of this post by SewingWithEase is to explain some of the most common problems with lower loopers and how to fix them.

What is a looper on a serger?

The main difference between sergers and sewing machines is their loopers. A needle is located under the machine’s needle and inside the machine. Loopers work similarly to knitting needles in that they overcast the threads of the needle.

Lower loopers provide the stitch’s stability, while the upper loopers produce the stitch that lies on the fabric’s right side or top. After the fabric has been trimmed by the blade(s), the upper looper and lower looper secure the stitch.

Lower looper thread keeps breaking

This problem is usually caused by incorrect threading. Make sure you cut EVERY thread (including the looper threads in the upper looper and the needle threads), then run the machine to ensure the threads are clear of the stitch finger and there are no stray threads caught in the needle plate.

Rethread the entire machine in accordance with the instructions in your machine manual. For example, the upper looper on the Brother 1034D serger is the first to be put on, then the lower looper, and finally the needles.

Furthermore, the machine should be threaded appropriately for the type of machine you have. Ensure you thread your serger EXACTLY, as shown in your manual since sergers are very finicky and very sensitive to even the tiniest threading error. The lower looper thread on the Brother 1034D serger must pass UNDER the upper looper thread in order to avoid getting caught on the upper looper thread. The lower looper thread should also be threaded so it goes toward the needles, not away from the lever, as the machine shows in the diagram.

Try replacing the thread if the thread is still breaking after you re-threaded the machine. It is possible for the thread to disintegrate over time, especially if it has spent a lot of time in the sun. Try switching to a new thread cone to see if the problem is solved.

Make sure you push the needles all the way to the top of the thread bar so that they point straight down. Note that they shouldn’t be even – one needle should be higher than the other. If that still doesn’t solve the problem, replace the needles with fresh, sharp ones.

Check to see if the thread is getting caught in any of the following places:

  • Check that the thread goes through the clips and tension dials correctly (some sewers even try to ‘floss’ the tension dials in order to remove lint).
  • Thread stress can be reduced by reducing tension.
  • The thread spools should be free of thread catching as it comes off, and the thread bar should be pulled all the way up.
  • Ensure that the thread goes directly through the needle’s eye and isn’t twisted around it.
  • Make sure the loopers are not catching the thread. An accidental needle strike can cause a burr on the looper, which then catches the thread. Do not try to fix this yourself if this happens to your machine – have it serviced. There is also a possibility that the thread could be getting caught in the lower looper of the Brother 1034D serger. Threads have been caught in the ‘hook’ on that threading lever. In order to thread that part of the machine correctly, you should not pull the thread all the way to the right of the hook on the lever.
  • Lint can build up in your serger, so clean it out using the small brush that comes with your machine and some compressed air that you typically use to clean computer keyboards. As lint accumulates inside the machine, threads can be tangled and broken. You can clean your machine by removing the needle plate if you haven’t done so for a while.

Lower looper thread keeps unthreading

Using the same methods suggested above, this problem can be solved by checking the threading, changing the needle and thread, then looking for places where the thread might be catching.

Serger needle is hitting the lower looper

Serger needles may be hitting the lower looper if you hear clicking sounds when you serge. Serger needles and lower loopers can hit each other when they are out of alignment, causing this problem.

Taking a look at your needles and ensuring they’re adequately positioned in the needle bar will solve the problem. As much as possible, push the needles up until they are at the needle bar, and make sure they are pointing downwards. Check that the needles you are using for your serger are the right size – a too large needle may hit the lower looper.

You may need to adjust the position of the lower looper or the timing of the lower looper in relation to the needles and upper looper if that doesn’t fix the issue. A professional should ideally be entrusted with the task of repositioning the lower looper and changing its timing. If you want to reposition the looper yourself, follow the instructions in this blog post if you’re cost-conscious.

The exact locations of machine parts vary from machine to machine, and the gauges that professionals use to get the positioning right are not available to us ordinary people. You’ll need a screwdriver and an Allen wrench to fiddle with machine parts because positioning is difficult (the exact positions vary from machine to machine).

Lower looper thread is pulling to the right side of the fabric

There is also the possibility that the tension for your stitch and your fabric may be off with the lower looper. In this case, the tension on your lower looper is too loose if the lower looper thread seems to be pulling onto the opposite side of the fabric instead of finishing at the edge.

If you have this problem, you should gradually increase the tension and stitch a small sample each time until you get a balanced stitch. An edge-to-edge stitch is one where both upper and lower looper threads reach the edge.

Lower looper thread is too tight and pulling the upper looper thread to the wrong side of the fabric

The converse problem occurs when there is too much tension in the lower looper thread, which pulls the upper looper thread in the wrong direction. A lower looper thread will usually cause ‘tunneling’ in the fabric when this happens. Stitch a small sample each time until you achieve a balanced stitch by incrementally loosening the tension.

Why does my lower looper keep unthreading?

To open the gap between the 2 looper eyes, you unthread the needles and turn the wheel. Firstly, thread the lower looper. Once it is threaded, pull it out gently and lay it on the serger backplate. Once you’ve threaded the lower looper, thread the upper looper next.


Although serger lower looper problems are often identified as the cause of stitching problems, the root cause may actually be elsewhere. First, check for other causes such as incorrect needle sizes or types, incorrect tensions, or wrong stitch plates. If those aren’t the issue, then you can move on to examining the lower looper itself. Check for damaged or misshapen parts, and clean or replace the lower looper as needed. With a bit of troubleshooting, you should be able to get your serger back in top stitching condition.

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