I found this old Black and Decker D500 vintage cord drill online for restoration project. I haven't yet restored many power tools and I thought this is just a clean up job, but little did I know the tool was making a terrible sound which had to be repaired before using. The drill had only a little rust, but it was covered in dust from the inside and had a lot of wear on the outside. All the greas was either dry or done. The terrible noise was coming from the rotor rubbing against the part around it. This was caused by loose bearing. I couldn't find a new bearing but I fixed the problem by filling the bearing with copper paste. It was only a little loose, maybe some tenths of a millimeter but that was enough to make contact. This is most likely not a permanent fix but it worked well when I tested it for a while. I can always add some more copper paste if needed. If I find a new part I will change it of course.