washing machine?

Hello. I have a Kitchen Aid Heavy Duty Superba washing machine that is around 3-4 years old. It has begun to make a terrible shivery noise when it is done with a spin cycle. I did have a service visit on it a few months ago and it only quit doing it for a short time. He mentioned he tightened a screw. It cost quite a bit to tighten that screw and it didn't last. Can you tell me how to tighten it on when it gets noisy? Thanks.