So, I looked inside my PX-2 finally, and the capacitors in particular look very new, like they'd been recently replaced. Some of the other parts look a lot older.
I'm trying to figure out why the autostop and arm return feature do not work. I'm assuming that the problem would be located either on the sensor board, the switch at the end which gets pressed when the arm is all the way on the left, or the cirquitry connecting that board or that switch to the rest of the unit. I took some pictures of possible culprits, but I'm at work right now so I will post them when I return.
Now that I've been inside this thing, I feel a lot better about working on it. Before I opened it, I assumed it would be super complicated, but it's really not bad at all.
I eyeballed the path of the tonearm wire, and I think I will attempt to rewire it at some point. It looks a bit old at this point and could probably benefit from new wiring. I'm still going to consider installing a junction box instead of using the native phono cable, as the native phono cable also seems old at this point. I know where to get a great deal on a special custom made phono cable designed for cartridge-level signals. I wouldn't use a regular interconnect cable. I think it would be worth trying, could be a good upgrade.
Yesterday I received a bunch of sorbothane pads and sorbothane feet. The sorbothane feet are the ones designed for washers and dryers. I didn't remove thethe original Yamaha feet, I just put the new sorbothane feet under the Yamaha feet, so the table is quite a bit taller now. I figure this way I'm getting the dampening properties of the original Yamaha feet AND the new sorbothane feet. They seem to be doing a great job isolating this table. I've never tried more expensive isolation methods, but I will play around with it.
Before spending hundreds of dollars on isolation, though, I'm strongly considering buying a peripheral ring clamp. Although I'm worried about it not fitting the PX-2 properly because the platter spins so flush with the table. I know that some ring clamps hang down past the top of the platter, like the ones that have weights hanging off the edges, so those wouldn't work, but I figure if I get a regular ring clamp it would work fine. I got a very heavy center weight last week, the Nagaoka Crystal GL601-II (694 grams), and it is also doing a great job. A ring clamp and a good mat would really put this table over the top for me.