I have a vintage Ferrograph Super 7 model 7504 that I haven’t played for a while. I got it out again, loaded a tape and started it. I know that it has been a while since I used it, but playback at 3 3/4 and 7 1/2 there is a loud mechanical noise ... louder at 7 1/2. At 1 7/8 it is not too loud. I took the front off and the noise seems to be emanating from the flywheel that is attached to the capstan. Is it my memory that is going or is there something wrong with the unit?