I wish you were close. Usually it takes a whole lot more than that to kill a Singer 500. I know you said you cleaned it. But here is info for a thorough clean up - see if you missed anything. You will need to start with cleaning the bobbin area. When did you last remove the bobbin holder? There is a little clip that holds it in. Check in your owner's manual. Lift up on the spring. Then the bobbin holder should just lift out. Thoroughly clean in that area including remove the bobbin tension spring and clean inside and out of the spring and the bobbin holder. Then put it back together. Put the bobbin tension back together and check the tension - adjust to flowing just about freely. Reinstall the bobbin holder per manual. Turn the machine over and clean under it - then give it a few drops of oil and some grease. While that bobbin holder is out give it a squirt of T-F under the part that moves around. Once that is cleaned, oiled and adjusted put the bobbin holder back in the machine - see manual for details. Then you will need to take apart the upper tension - clean everything, including the pin. Re-assemble and adjust. See manual for how it all goes together. ArchaicArcane has a ton of tension adjustment info on her blog.