1999 Sony SLV-M91HF vcr problem

[pac.attack76]

Just got this one in and it played great through 2 movies, then through every movie I play, about half way through on every one, it starts stuttering every few seconds and increases to nearly constant distortion per every other second with slur in audio like it's trying to hang up or being pulled or speeding up for a split second each time. Sometimes, running the jog dial backwards a few seconds and letting it play back corrects the problem for awhile but it comes back in time. But that so far has only worked twice out of maybe 5 or 6 tries. Is this a lubrication issue or dirt? When it plays correctly, it's clear as heck. Also, could it be an overheating issue or friction? If it'll help, I'm going to be posting a youtube video of it running after it starts messing up. I should have it up in a few days and can put link here.