I was sewing earlier today with my Bernina Record 730. I've only had this machine for a couple months and it's always been kinda noisy. The mechanic at the Bernina dealer/repair shop has been wonderful , showed me a couple tricks and told me he has an extra motor when I need it. Today I discovered that it was skipping stitches so I thought I'd clean and oil and see if that fixed the issue. The cleaning process (sometimes) includes using the air compressor to blow out the dust from the lower compartment. Today, thanks to the compressor, I discovered an extra screw has been floating around the lower compartment - probably since I've owned the machine. Since then, it's no longer skipping stitches and is actually much quieter. I see nowhere that looks like it's missing a screw, so when I get a chance I'll take it to the Bernina repair guy and cross my fingers that he can figure it out!!!

I would tape the screw to the outside of the machine so it doesn't get misplaced. It may not even be to your machine.

If its a very short screw with a very large head, it has come off of a foot. This is very common. So the screw is not likely part of the machine. The bernina feet have a screw that goes on the back of the foot. This can be used to hold items to the foot for advanced operations. These often come loose, fall off, land around the machine and cause a lot of anxiety. They rarely cause any problems. Hope thats all it is!

It must be the screw that my Jamone 6500 was missing. From the time I bought my machine, I couldn't get the feed dogs to come up high enough to feed fabric in evenly which affected the length and eveness of the stitches. Eventually another Janome dealer discovered that my machine was missing the necessary screw and it wasn't in the bottom of the machine so may have never been inserted in the first place. One small screw can definately be a problem.