It's funny about the amps I have especially the Phrase Linear which were Carver's first entry into Stereo amp's. Heck, I've had them for over 45 years, not tubes, but very heavy power supplies. Anyways...make a long story short, over the years I've chatted with specialized repair shops(they still work) about doing once overs on them. Of course over the years, many upgrades in tolerance's in the actual components of the amps(capacitors, resistors...etc etc)have been made available so now the upgrades cost more than the amps did in the first place. I realize in todays world 400.00 isn't a lot for an amp but 45+ years ago on a super market clerk salary, 400 bucks was a small fortune!!! :-) :-)