I have a Singer that is a little bit older than yours. About 20 years ago, I had a lot of problems with the bobbin. I bought a new bobbin case and everything got immediately better. They do wear out. The needle can hit them and jar them and cause problems. I couldn't see anything wrong with the bobbin case that was in the machine.

Sewing Machines Plus have been helpful for me when I needed parts. If you believe the bobbin case is the problem, I would call them. These are the bobbin cases I found on the website: https://www.sewingmachinesplus.com/s...a+bobbin+case#