There are circuits on manuals on line.
You will not fix this unless you have comprehensive test equipment.
Looking to see what is burnt will not get you far. Usually what is burnt is effect and not cause.
Since it blew fuses and the output transistors blew, it is possible something was creating DC off set. Now that condition still exists and the unit is in protection from DC off set.
These plate amps are very complex and hard to service and not usually worth the trouble.
If you don't already have scope, generators, variac, FET VOM and quite a bit of experience, you are not going to get this up and running.
I can tell that amp was designed for that sub, as there are limiter and Eq circuits, so it won't be the same sub if you just use a different amp.
