While listening to a tape, motor grinds to a halt. So what is up now?
Take off the cover. Hard to believe I had all the screws installed! Checking with a voltmeter, there is only a few tenths of a volt across the motor but normal 10 V at the input to the regulator circuit. With the motor disconnected, the output of the regulator is exactly correct – 6.3 volts. So the regulator is most likely fine. What about the motor. Testing with an ohmmeter reveals that the resistance varies between about .5 and 2 ohms – much less than I would expect. So, there is a problem with the motor. It is extremely unlikely that the entire motor shorted out. This is the classic partially shorted Mabuchi-type motor scenario. I am not going to let a little motor get the better of me! I first try spraying it out with some degreaser – no dice, no change. I will just have to take it apart. The end-plate is held on with a couple of bent metal fingers, pry them out. However, I cannot just pull the end off as it will rip the delicate metal brushes in the process. There are two access h
