Malfunctioning Yamaha TT-300U

Hey all,

I've got a malfunctioning Yamaha TT-300U and was wondering if anyone might be able to shed some light on how to remedy it. My system, which includes an Audio Research LS2, ADCOM 5500, Phono Box, and Klipsch RP 160-M's has been running great. Recently, I jolted the tonearm on my TT-300U and now it won't stop spinning when plugged in. On top of that, when the tonearm is placed on the record, it goes limp and drifts off to the middle of the record. Since it's an old model, I've had trouble finding anything online about this issue and the turntable in general. Has anyone had the same problem? Only thing I've been able to find out is that the issue may stem from a jolted microswitch, but I don't want to open up the turntable if possible. Is this even worth fixing? Any help would be greatly appreciated.