yes, it sounds like you've got some power amp problems.
though I think it is just as likely that the previous owner made the mod, and used it as just a cabinet. which caused the power amp failure. hard to say.
if you are not familiar with repairing solid state amplifiers, it might be best to let someone else take it on.
its just as likely that you will have to replace resistors and capacitors as it is transistors. hard to say which ones without testing.
do you have a multimeter?
though I think it is just as likely that the previous owner made the mod, and used it as just a cabinet. which caused the power amp failure. hard to say.
if you are not familiar with repairing solid state amplifiers, it might be best to let someone else take it on.
its just as likely that you will have to replace resistors and capacitors as it is transistors. hard to say which ones without testing.
do you have a multimeter?