I have an PSLD45 that plays side A fine, but as it automatically switches to side B the RPMs increase beyond play speed and then the unit reverts to stop after about 20 seconds of high RPM fruitless spinning. Any thoughts or suggestions? I know...can of gas and and a match. all other functions work perfectly. Manually switching from A to B during play works perfectly as well!

I want to say it sounds like the rubber mat is slipping.
Does this happen with all discs?

That’s my guess also, slippage between the disc and the spindle.

I'm quite convinced too that it's most likely a dirty rubber mat on the spindle.

I had my newly acquired Mitsubishi M-V7057 serviced today to replace a stretched loading belt and afterwards when I tried an LD I noticed slipping as the disc was spinning up. In addition, the slipping appeared to also prevent the player from wanting to go to Side B as though the machine thought the disc was an "LD Single".

I cleaned the mat w/ Intraclean (won't dry the rubber like alcohol), tested again, and everything played correctly as it should. The player is good as new again.

OOOps....fell off the LD wagon for a bit there. The problem described usually occurs with older discs (CX sound), but does occur sometimes with newer discs (digital sound). I'm VERY curious as to why the RPM's increase so dramatically before it gradually (30+ seconds !) comes to a stop! This increase in speed is waaay beyond the normal play speed. Regardless, I will take the cover off the unit and attempt to clean the "mat" . Is there any other product I can use besides Intraclean? I live next to Home Depot! I appreciate the input!

Nothing too strong, I believe grasshopper would use windex but I can't remember right now.
Nothing that will melt the rubber just clean it and not leave any residue.

Do you hear a squeal as the disc begins its speed up?

If so, then you probably need to clean or replace the grip ring. However, I would replace the loading belt first since it could also be that causing the issue since it may not be pushing the spindle motor tight enough against the clamper assembly and thus create slippage because the assembly is not grabbing the disc tight enough.

I have experienced exactly what you described while performing centering adjustments. I wouldn't worry about any of that though until you clean/replace the grip ring and belt. Most of the time it is one of those two.