Juki sewing machine keeps sewing after releasing foot pedal

are you physically turning the wheel backwards? if so .. you can't do that ..the wheel will turn any direction but will only sew in one direction.. use the reverse lever or you can life to foot and place it back and re-sew over the stitches.

ask JUKI yet?

Question edited for clarity, spelling and capitalization.
Question moved from category 'Cars and Trucks', to Juki sewing machine.

When was the machine last serviced? They should be serviced every 2 or 3 years. Most people never service until they fail and then wonder why they failed.

Slow, weak sewing would be caused by the foot pedal having dirty contacts n the insides. It has a wire wound track and a contact terminal.

The fact the needle doesn't go up and down is either caused by it being in bobbin winding mode, or a link has come off inside.

So first thing to do is open up the foot pedal and clean the contacts with electrical switch cleaner (NOT WD40). Then check you aren't in Bobbin winding mode, normally a clutch on the hand wheel.

Or

Take it to Juki Service.

Videos and the Service Manual in the link

https://www.google.com/search?q=Juki+HZL+29+Service

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Mine did that very same thing. There is a sensor in the foot pedal that was faulty. I replaced the foot pedal.

It is generally because you have not taken your knee completely off the knee lift.
Whenever you use your knee lift, it opens the thread tension and lets out more upper thread.
If you find out you are not leaving your knee on the knee pedal, try to only lift the foot as little as possible when you do your turn. I find out that when I am in a hurry I leave my knee against the knee lift as I am sewing and I have the same problem.
Good Luck. :)

No, a serger does not reverse. To sew back over the stitch, you can raise the presser foot (do NOT cut or pull the threads) and "flip" the fabric over, lower the presser foot and stitch.

have the control pedal check for problems

Be sure that the stitch length is set to a higher number. The closer to zero it is set, the closer the stitches will be until zero when it will actually be sewing in one place.

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there could be something wrong with the foot pedal, it may need to be serviced or replaced, or there could be something wrong with the plug where the foot pedal plugs into