Did you measure a "lowered sound floor", or is that a subjective judgement based on listening to LPs?
The latter, Lewm. It was the proverbial, "I could hear things (on very familiar records) I never heard before" bit. I did buy a mechanic's stethoscope. I placed the probe on the spindle shaft and the bottom of the motor: I didn't hear anything. Suspecting that the scope is not sensitive enough, I put it on a DD table I use to clean records: a hum could easily be heard. Of course, this does not get me very far, since I didn't probe the old bearing or the redline.
Your suspicions re a heavier weight Redline oil are duly noted. I might test that out in the near future, either a heavier weight Redline or a lighter weight RP.
The bearing is accessed from below; you'll need to flip your table upside down. Then unscrew the giant brass screw; it may be secured with some kind of cement that you'll need to remove first.
Your problem with your tt 101 is puzzling. I recall you saying that you could hear your platter scraping. Did you fix that? There are two ways to adjust platter height: the bearing screw at the bottom of the table or shims between the motor and the chassis (there should be 2 of them on each of the 3 screws that secure the motor. Note that with the screw, there is a range that yields the correct motor height(s). Outside that range, one gets one of three things: scraping platter, errant rotation, or complete locking. The easiest way I've found to find the right height is to take black bottom cover off and place your table inbetween two suitably spaced endtables. This way you can access the screw from below while the table is running. Just make small turns to the screw (clockwise--as seen from below--to raise platter). I know you have a stethoscope: use it to hear whether the platter is scraping.