I recently picked up this Sony Walkman WM-F10. The tuner and cassette are both in working order, but for some reason during tape playback, changes in position will cause the audio to wax and wane, come in-and-out, get louder and softer. Any idea what this could be and how I can go about fixing this problem. I have also noticed that when I stop the tape playback I can hear the motor slowly coming to a stop; it takes about 2-3 seconds for the motor to fully stop.

Thanks mates!