My theory is that either the felt mat or the vacuum hold down on the Sapphire, or both, hindered its performance, with an added possibility that the Sota was unstable in terms of speed. Before anyone takes too much offense, I do believe the modern Sota TTs are much better.
@lewm Oops, that's a caveat I fail to mention - the older series Star platters (III and earlier) feature short & stiff rubber lips that don't make a good seal. Even back in 2007, my III couldn't make proper seal, and despite the vacuum pump working fine, the un-suctioned rubber lip prevented records from making solid platter contact. I'm not sure if this old lip style ever worked very well, but with age they definitely don't. You really have to either tape it down or cut it off. Maybe that was a partial culprit in your case, or maybe not.
Nova Series V and Cosmos IV and newer use much wider and more supple lips that work very well on all but the most warped records - though you do need to clean them regularly.
Besides my old Star III (upgraded to Nova V) I've added a factory refurbished Cosmos IV+ (adds some of the new tech from Phoenix Engineering) and it's a wonderful table IMO. The older exotic woods were a lot prettier, though :( This one is an orange-ish walnut finish which is truly the ugliest walnut color I've ever seen.

