put in a new fuse and take out the power tubes (remember which sockets they came from). power up the amp...does the fuse hold? if no, your problem is something other than power tubes....bad resistor or cap probably. if the fuse holds, put in the outer pair of power tubes and flip into 60watt/classA mode. does the fuse hold? if not, one of those outer tubes is bad. if the fuse holds, chances are one of your inner pair of power tubes is bad. probably not a bad idea to replace all 4 if one is bad
