Did the tt used to work okay before it started doing this?
If so:

The screw that secures the tone arm tightens itself over time and causes this.
Normally the record will move randomly by itself an inch or so, sometimes more sometimes less.
Might possibly be that- doesnt need to be undone much at all.

Ok. I'll try loosening/tightening the screws tonight. Is there a "balance" of the tightness or looseness of the screw that allows the TT to work flawlessly? If it is too tight can it cause the tonearm to jump?

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I loosened up the screw tremendously and it works brilliantly now. Thanks bro.

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common problem- Its worse when it happens in a live situation believe me!
Glad it fixed it