Bottom line: I don't see this mass centering made any difference.  Although I did get the mass within spec, and it remains so, it was difficult as in it took many attempts.  This may still indicate that the machine is not well enough leveled or still something more difficult to fix.

Attached are spectra of the STS2-B (ITMY) and STS2-C (HAM5) and coherences between them early Tuesday and Wednesday morning to compare them before and after the centering done yesterday, I adjusted the times to avoid an EQ Tuesday am.   STS2-A remains rotated out of position so is not included in this comparison.

The attached spectra and coherences don't reveal any great improvement from the centering.  The reference traces are after and the current traces are before the centering.  The coherence and ASD continues to show that the Y channel looks pretty good and the X and Z channels much less so.  If you look at the STS2 channel/axis orientations (see second attachment,) you'll see that the Y channel does not use the U axis sensor, and, the centering of the U axis was the problem axis.  This is why I want to play with the level of the U axis and continue this examination.