Originally Posted by Pete240885

Ok this is what i think should be done as although the falirue was identified the reason why is not known it is entirely possible that they could be blown again although i'm hoping it was just a power surge that caused the problem:

First question is the cost of these transistors significant to you, if it is then get back to me i'm trying to analys current flow through the amplifiers output stage but its nature is slightly different to the output stages i have studied so i'm going to re-check my working tomorrow afternoon and make sure I agree with myself.

If not go ahead and replace both of them, let me know the result,