I have a Technics SP-15 direct drive turntable. Suddenly today, when I turned it on, it started running at about 500 rpm. That is a guess, obviously, but it is running out of control. I hit the various speed buttons with no effect. Off and on, it would start at the correct speed, but then suddenly it speeds back up to the fast speed mentioned. I want to stress that this is not a matter of it running at 78rpm +/- 9.9%. It is literally spinning at several hundred rpm. There had been no sign of problems with this unit up to this point. Any suggestions on a place to do repairs for this sort of thing?