My over locker jumps the stitches - Sewing Machines

Check the threading.

Does this one work?

https://www.sewingpartsonline.com/needle-plate-elna-604e-sewing-machine.aspx

Ive had that happen on other machines. I used tape to close the opening in the top of the takeup lever--no more jumping out. Be sure to ALWAYS RAISE the presser foot when threading the top thread.

Your gonna need a machine with a over locker on it.

Timing issues are usually caused when the needle hits something it shouldn't, ie a pin or if the sewist pulls the fabric while stitching or the fabric is too thick and causes the needle to bend....

There are web sites and videos on the internet explaining how to address sewing machine timing issues. Or, take it for service.

...

Sounds like your blades need to be checked and/or replaced. Take it for service.

FWIW, it is not advisable to disable the blades when stitching. It is too easy for the fabric to extend too far to the right and end up impacting the loopers causing damage or breakage.

...

Perhaps this will help:

Overlock Serger Troubleshooter

Serger Stitches 101 Cheat Sheet Never Ever Without It Your New Must Have...

Could be a timing issue.

..

Is something jammed? Does it move at all? Pull out the threads and check all tensions for a blockage. Does it move at all when not threaded?

Tension settings on an overlock machine vary by the stitch you are trying to accomplish. You can usually fine the correct settings in your manual. A good trick to setting tension is to start with 4 different thread colors so that you can see what thread requires adjustment.

What stitch to you have selected for it to do? Please check to see if it is set for straight stitch only.
Linda at Relics
www.sewing-machine-manuals.com