I don't have a Janome, but this has happened to me on my Pfaff. Look in your manual for installing the quilting guide or darning foot and you will probably see that screw. On all the machines I've used over the years there is a thumb screw that inserts at a downward angle (impossible to see the hole) to keep the quilting guide or darning foot in place. It is easy to accidentally unscrew the screw just rubbing fabric against it repeatedly, or it can vibrate loose to the point it will fall out. After I do any FMQ I make sure I re-tighten the screw in the hole so I don't have this problem.

Put the screw in your bobbin box for your machine till you figure out where it goes. This way it won't get lost. Hope it gets resolved! Jan

Are you sure it didn't fall out of the pocket of the jeans?

Could it on the side that holds pressure foot base. Mine came off and I just bought the one that was bigger and have never lost it again. On left side of machine

if the machine still works, don't worry!!!!

This is too funny because I was sewing yesterday and right in front of me is a hole for a screw but no screw. Haven't a clue!!!

If your machine also does embroidery, it may be the screw that you use to attach the embroidery foot. There's a hole on top of the regular presser foot assembly where my thumb screw is attached. Check for that hole - and look it up in your manual. It 'shakes' loose if you don't give it a twist once in a while, and I'll bet that's what happened.

Are you positive it didn't fall out of the jeans pocket?

send us a picture of it laying beside a dime for size. then mabey we can help.
phyllis nm

Sounds like it might be like the one I have in the back of the presser foot to hold the guide that goes with my walking foot to follow along the previous stitching line to keep lines straight. I like to never have found where mine went the first time it fell off. You never look back there.