Hitachi SB-75 Belt Sander Diagnosis Sander Belt Pulling to Side and Stopped Running

I was using this sander to do some hard work stripping paint off very old weatherboards when the belt started pulling to one side and even coming off despite adjusting it, and then the roller stopped turning at all, even though the motor was running. It had been making a few squealing sounds before that, and is an old machine that had done plenty of work. I pulled it apart to find faulty roller bushings which can be removed and replaced. My neighbour who owns it offered to get the parts and reassemble, so I left that part to him.