I've got a QL-Y66F that I bought new back in the eighties and am still running it. The tracking force, q-damping, and anti-skate will act up sometimes if you don't move the adjustment wheel knobs around from time to time. My tone arm was smoothly dropping onto the record then abruptly losing (or gaining) tracking force and bottoming out . At first I thought the suspension on the cart had collapsed but it was OK. Then I thought one of the chips inside the table had finally given up. I was about to write my old friend off and on a whim I turned the tracking force wheel back and forth a few times and everything went back to normal and has stayed that way for almost a year now. My old friend refuses to die, it just wants a little attention every once in a while. I don't know for sure but maybe a bit of contact cleaner would help with this. Enjoy your JVC, I'm certainly still enjoying mine. One other thing, these tables work very well with LOMC's.
Regards, Sam