I recently bought a RC-M50C, and it was working when I got it, although it needed some work. This morning, I tried to use it again, but the tape motor won't turn and the speakers make a humming sound. The speakers also make a popping sound when the power switch is turned off. I haven't tried line in, but it seems the radio is no longer working either. When I first noticed, it was plugged into AC in the wall, but the same symptoms appear with batteries. Could this be due to a failed power supply? If not, what could it be?
Update: Line in and radio work properly, but the capstan motor doesn't turn.
Update 2: Capstan motor is getting power, but there's too much friction for it to start on its own.