@audphile1 My suggestion to be made, and now one that is given a substantiation by your own report, is to seek out Valve Exchanges that are recognised to work very well with the RC1 Schematic.
I have had a experience on a few occasions doing this, and the end result was remarkable.
A $1600 Amp + $400ish in Exchange Valves, might just convince the Amp is worthwhile staying on with and keep $7K in reserve.