Fan on Amp Unbeatable

Depends. Some run whether needed or not. If not then simply disconnect it. My Dynaco was like that, a simple socket mod let me leave it unplugged most of the time. Usually need to be driving them pretty hard to really need a fan. If it really is needed then remove it. Hopefully find something with a part number on it. Because unless you are lucky enough to find its a simple clean and lube then its gonna be replacement time.

Fans in SS power amps are because the designer was cheap when it came to heat sinks.

That is why there are so few with fans.

I have had a few Pure Class A amps that got extremely hot and had fans.  I replaced the fans with high speed quiet fans,  then used resistors to slow them to a tolerable point for noise.  My amps lasted and lasted.  You might try that. 

If the junction temperature exceeds 90 degrees C, your output transistors will have very short lives. You could monitor their case temperature with an inexpensive (read somewhat inaccurate but close enough for this purpose) IR non-contact thermometer. Refit with better heat sinks and use computer grade thermal compound.