The knob to move the needle up and down won't turn. What do I do?

SOURCE: Handwheel on Sewing machine no longer moves needle.

Actually you should have a "set screw" in the hand wheel. The set screw is usally locked down tight to keep the hand wheel from spinning freely. I f you can run the machine slowly and hold the hand wheel in one place but the machine continues running, then you do need to replace the "set screw". If you replace it you will find that you can offset some of the machines vibration by where you lock the wheel down. Trial and error is the only way to achive this adjustment, kind of like balancing the tires on your car.

SOURCE: Bobbin Winding

How do I wet wind a 2 inchs long bobbin using varnish.

Thanks
Gholam

SOURCE: My needle will not move

check for thread jammed around the bobbin case and hook area (where the needle goes in the machine)

SOURCE: janome mylock 634D overlocker

this very same thing happened to my flat machine turned out to be a piec of material jammed in the workings also wrong oil used or it might be thread jammed try and see

SOURCE: When I turn the knob

Have you removed the bobbin case to clean it? If so, it probably needs to be reseated. Remove the bobbin. Take out the case and reinsert it. If you can't get the bobbin out easily, there is probably thread clotted up somewhere under the feed dogs. I usually gently rock the handwheel back and forth as I brush the bobbin case area to begin dislodging the "clot." It also helps to remove the throat plate so you have a better view of the mechanics under the feed dogs. You'd be surprised at all the goop that can be caught but you can't see. If you do find a thread clot, use a machine brush and tweezer to gently remove each thread bit. I really hope this helps you. If it does, please come back to Fixya and rate my advice. Thanks!