How do I thread my overlocker

Two things make sure your threading it in the right order. your upper looper first then your lower looper then your needles. If your doing that then change your needles and if your using cheap thread on an overlock it just wont sew right. You need to use a good quality thread on overlocks. Hope that helps

The 335 has a two thread chain stitch (stitch type 401), and the overlock side (right needle side), is a three thread plain overlock. If you are describing the plain overlock as the problem, I would first suggest the following in re-threading:

1. Thread the upper looper
2. Thread the lower looper
3. Thread the needle last (important)

If the needle threaded, you cannot re-thread the lower looper without breaking the thread.
In order to thread the lower looper, the lower looper must pass by the needle thus picking up the needle thread. So, instead of threading the lower looper thread underneath the needle thread, the looper would be threaded on top and cannot sew without breaking the thread.
Make sure that the threads are bedded between the tension disks. Check this by stretching the thread fore and aft of the tension disks as well as visually noting that the threads are not accidentally threaded behind the disks. You can also loosen the tension disks when threading so as to allow the threads to bed deeply between the disks.
Please reply with your observations.

try adjusting the thread tension to that needle and check for burrs along the threading path and on the needle plate

the tension maybe to high, try loosening it a bit

Many things can cause the thread to break on a serger. Timing, position of the thread guides, poor thread, and improper tension. One common error is the failure to thread it in the proper order. If the needle are threaded before the lower looper they will cut your looper thread.

Overlockers and or Sergers are ALWAYS threaded the same way. Upper looper, Lower looper, right needle, left needle. If you have a model number for your Juki we might be able to find you more information.

The best way to figure out tension problems is to thread each thread in a different color so you can determine which thread is giving you problems.

These machines can be frustrating and EVERY time the thread breaks you MUST start the threading problem from the beginning... upper looper, lower looper, right needle left needle.

globe overlocker stitching reverse

I was having the same problem. I was trying to thread only that 4th one because it keep breaking. It did not stp til I rethreaded all the threads and did it worked fine

I had a similar problem with my machine. What I've started doing with mine is setting the stitch length at 3 and the differential feed ratio at 1.0 then I set all 4 thread tensions at 3. I thread the machine from right to left, and then when everything seems to be working okay I take scrap material to test the tension and then set them to suit the material I'm using. Right now I'm working with a twill so my settings are 4-4-5-5. This seems to have stopped the thread slipping off the bottom looper and I haven't had any more needles break. I hope this is helpful.

One of the most common mistakes with overlockers is that the threads must always be threaded in order. So if you sew about 1 inch and the thread breaks try unthreading the eyes of the needles rethread the looper and then rethread the eyes of thew needles. If not you will get the same result of sewing about 1 inch and it will break again.