Hello and welcome to the Carver site.
If you do a search for information on the PT1250 you will find out that it is a rebadged PM-2.0t. So download that manual.
In it you will find more information than just the schematics that are in the 1250 service manual.
In the owners manual for the 1250, it does as @Yamacarver indicated have individual CH1 and CH2 thermal protection along with three other protections. How all this interacts is a question for someone familiar with electronics and maybe this unit.
I must ask this next question so excuse me if you performed this..... Did you check the fuses, in and out of the holders?
If it did indeed overheat I might be concerned about the thermal compound between the mica insulators, transistors, and the heat sinks just due to its overall age.
This is the extent of my experience/advice so Good luck in getting your units working again.