Those -X6/7 series TTs....
were very good and solid as a rock. I had one when they came out (sold 'em, too) and they never failed to deliver. A few years ago, I bought one, tho, which had a couple of problems:
* Speed was erratic, especially at 45RPM. It would run fine for a while but then slow down then speed up again.
* The damped cueing mechanism didn't work - all the fluid was gone.
So, on the speed problem, I discovered that the voltage regulator would change its regulated voltage once warmed up. It only took a minor adjustment - on the board - to get it back in again. BTW, there are *lots* of wire-wrapped connections on the boards, which I soldered to remove the possibility of them causing problems later.
On the cueing mechanism, I never did figure out how to disassemble it without removing the entire arm from the plinth. I finally decided it wasn't worth it. My son now uses it.
Other gremlins to watch out for:
* The 4 feet are adjustable to level the TT but beware that they use a plastic threaded shaft. Any pushing of the TT will cause them to break without fully picking up the TT as you move it around. You can, however, improve them by using a small nail with its head cut off. Insert it down into the threaded shaft on each foot. Use some epoxy on the end of the nail to keep it in place. These things are unobtainium unless you find a donor unit.
* Do *not* clean the inside rim of the platter. This contains a magnetic strip used to determine the rotation of the platter for the speed locking circuits. Also be sure that the pickup, a silver item, is clean and does not have dust in the way. Don't adjust this unless you have the correct instrumentation and the service manual.
Hope that helps.
Cheers,
David