I was the product manager over all power amps at Peavey when the CS800s was introduced. It is in fact a decent amp...
While the memories are a little painful there was an issue with a thermistor**** going through a hole drilled in the heatsink to sense temperature that was a little too fragile and inclined to fracture. The amp thinks it is over heating, when the thermistor is broken and open circuit.
#1 contact Peavey Service... They are surely familiar all the likely suspects. It is a relatively simple repair and IMO the amp is quite respectable when working properly, albeit a little puny at only 240W @ 8 Ohm.
Good luck
JR
*** the sad story is the thermistor vendor had just moved their manufacturing of that part to China. The samples they submitted to purchasing/engineering to approve all worked perfectly... It was only after the amp reached full production that the sierra hit the fan. I still have scars from that, but those scars have plenty of company.