Reply to Technics 1200mk2 skipping and tonearm not correct..even after tonearm replacement

I have a Technics 1200mk2 that didn't "play baseball". By this I mean that when the weight is all the way back, the tonearm does not move on its own when antiskate is adjusted. It never caused a problem for me in about 3 years, but then it started to act funny. In Serato it would stop, then slowly turn backwards, then forwards, then freak out, then randomly start smooth again. So I replaced the tonearm.

Didn't do a thing.

Now what? What could be causing this issue if the tonearm was replaced?