@rvpiano Your is one more story worthwhile adding to the threads about Third Party Services treating a Cart' in need of a professional service.
I am an advocate of this methodology to have a Cart' overhauled and returned to service.
My Rebuild, that is in use at present, was compared to another Cart' on a few occasions. The first being demo'd at very low hours, followed by approx' 100 hrs and at approx' 200 hrs of usage.
The Cart' has been demo'd in this same system on later occasions as well, especially against other Cart's that are temporarily available.
The comparisons were 'all' on the same TT>TA>System to a Cart' from the same Brand, that was the Brands TOTR model from an earlier era, this Cart' had less than a few hundred hours usage, at the first comparison.
The rebuild shared some added components that the TOTR Cart' has in use for the design.
The voicing was very similar on all occasions, and my own Cart' certainly become a very worthy contender at the approaching 200 hrs of usage demo', this was when both Cart's Bass Notes were extending to almost identical frequencies and were decaying in a almost identical manner, it was the Mid's and Highs that were most noticeable for having a difference to their voicing.
Silver and Aucurum Coils / Boron and Beryllium Cantilevers, as well as the Cart's Body Mass, will be quickly identified as being responsible for voicing variation.
What was learnt is that Cart's can take time to find their true voice, and my build choices were seemingly very much in favour to all who were at the demo's.