My vintage 301 singer was sewing great until I rewinded the bobbin. The stitches on the botton are very loose and wavy. I don't know how to fix the stitches. Thank you for any help. judy

Did you accidentally put the bobbin in backwards?
Have you tried rethreading everything with the presser foot up?

If the bottom stitches are messed up, the problem is on the top. Rethread, check the needle, make sure everything is in the right place.

Wow are you me!!! I had the same problem yesterday. My 301 was totally rehabed and working great, then yesterday I figured I could use to do my paper piecing...wound bobbin and stitches were off on the botton...so loose...Tried redoing bobbin same problem, tension same...Guess I'll start from scratch today and see what happens...Must be something with the bobbin and the way were putting it in...

If the stitching is goofy on the underneath, it's a problem on the "top" of the machine, Goofy stitches on the top of the fabric means something is wrong with the bobbin. Re thread making sure everything is where it should be. This rule of thumb works almost 100% of the time. Has saved me lots of time and trouble over the years. Good luck!

I rethreaded and pulled bobbin and redid that and all is OK...thanks