Turnable database with TimeLine

Tony, Those are very interesting observations. As you may know the horizontal movement of the SME upper platter is also constrained with paddles in silicone in the towers. The vertical movement is less so I think due to the direction and design of the paddles. What you have done with the rubber shims may have a similar effect.

Do you happen to know if the last time you played these same cuts whether or not the speed was off by that 5 Hz? I ask because I listen to Muddy's Folk Singer at 45 RMP and I just cleaned the drive and platter pulleys and my rubber belt with lighter fluid and reversed the belt as per SME recommendations and measured the speed. It was off by a fair amount relative to the last speed check. I had to click the speed buttons about 6-7 times (<1Hz per click) and listened again and heard similar improvements to what you describe.

So, my point is that what you are hearing may be either a result of the restriction of horizontal movement, the correction in speed, or a combination of both. But is sounds like things are definitely improving.

Yes, my speed was within 1.5Hz of 3150Hz before. One thing I can do is recheck speed after I remove the shims and see if it shifts down. The other thing that I found last year with the iPhone app was that the tt must run for a couple of minutes for speed to settle in. I don't know if the motor must warm up, the electronics or the platter bearing lube.

laser gets the mark in every rotation

Not quite......
Laser starts off under the H in the word FRUHBECK....and ends up under the letter K.
Therefore the RX5000 is running fast....and that's in only TWO minutes?
By the end of a record.....it would be off the page completely.
Hardly competitive with the Raven's performance?
And what about lifting the arm off the record to show the performance WITHOUT 'stylus drag' as is shown with the Raven?
Is that a bit too revealing........?

Tony, From your description, it seems you have an older SOTA tt. So far as I know, all the later SOTA tt's have eliminated the very real problems inherent to a belt-drive design that mounts the motor on the chassis while suspending the platter and bearing. (You've described them well.) You might consult SOTA and let them "fix" it or let them tell you how to do it.

In the 90s, I lived for many years with a Star Sapphire Series III, which is built their "old fashioned" way, with motor mounted to chassis. I thought during that time that it sounded "pretty good", but I was not yet a total analog nut job, as I am now. Words cannot express how much better analog can get compared to what that SOTA SSIII gave me, in retrospect. Even my next tt, the Notts Hyperspace, with its stretchy rubber belt and weak motor, just absolutely killed the old SOTA in terms of pitch stability. The Lenco and all of my dd tt's take that to yet another dimension, adding more drive and open-ness to the music. You've gotta try it. Timeline, Shmineline.

It is a Series III from the 90s. I think that is good advice. I will check with Sota. I had the impression that only the Cosmos features a sub-chassis mounted motor with the platter and tone arm. I also have some ideas that would be reversible, to try out on my tt to fix the horizontal axis.
This thread has been a good learning experience. I bet a number of people suspected suspended tables didn't hold speed as consistently but didn't really understand why. I knew before that any movement of the turntable due to footfalls or just pulling on the cue lever affected speed; but I didn't realize til now how much the variable drag by the stylus would affect belt tension and ultimately speed. Plus, the improvement in detail and distortion that I experienced with better speed control is an eye opener.