@skids
2019 I bought a very old Vintage Tube Preamp, too old for McIntosh to check on because they no longer stock all the parts for it). Audio Classics, very near them in Vestal works on them.
Lucky me, seller didn’t lie, sounded great. Two years later, I visited a friend in Vestal, dropped it off. They replaced a few resistors and capacitors, one LED, all my tubes tested good.
Next visit to my friend, picked it up. Got it home, sounded the same, maybe younger ears would notice something, but I had more confidence in it of course.
What made me very happy is that they replaced all the old rca jacks with new gold plated RCA jacks. I occassionaly had l/r imbalance and found the signal intergrity of the old worn jacks was inconsistent. I think they were originally slightly undersized, or, cleaning them repeatedly made them a slight smaller diameter. Cables are damn tight now, and I changed all my RCA’s to Locking Connectors, so if I mess with any cable it doesn't disrupt another.