[QUOTE=mcadwell;8472839 My only problem is getting the bobbin thread to run correctly through the shuttle. It takes several tries to get the thread in there correctly so the thread easily pulls out. Sometimes the bobbin gets stuck and won't move at all. I'm thinking of getting a new shuttle to see if that helps.[/QUOTE]
Have you taken the tension spring off the shuttle and cleaned it all up? You can clean out the inside of the shuttle as well if you haven't done so (I have used a bore brush to do this). If you take the spring off, this will affect your bobbin tension. If you remove the spring you can first tighten the screw all the way down, counting the number of turns of the screwdriver from the current position of the screw to when it stops. Then when you replace it you can tighten it all the way down then back it off the same number of turns it took to tighten it; this should approximate the same bobbin tension.
If you replace the shuttle I would look for an original Singer part. I have tried the modern copies without any success, lulled into purchase by the price being about 1/3 or less of a "real" shuttle.