Audio Systems: Phase Linear Model 700B, solid state amplifier, massive heatsink

Question
Dear Gary,
I'm pleased to still own a mint condition Phase Linear Model 700B direct coupled solid state amplifier (350wX350w). I've always operated the unit with the rear mounted selection switch in the "normal" position (as opposed to the "direct" position) because it is only used at lower listening levels in the stereo mode. In addition, it has always had an external cooling fan to cool the massive heatsink assembly, next to the massive (heavy) transformer. Approximately twenty years ago a condition developed whereby when powered-on, the one AGC 10A line fuse blew (this unit employs five protection fuses, one AGC 10A line fuse and four AGX 5A supply fuses, all rear mounted). After finding a repair shop in Boston to fix the unit, I enjoyed many hours of listening pleasure. I've recently pulled the amp out of 15 years of proper storage, only to find that the AGC 10A line fuse blowing condition (when powered-on) has re-occurred. What could have happened during such a lengthy period of inactivity to cause a second time repeat failure, and how can I ascertain that a correct/time lasting repair is made? Thanks in advance.

Answer
i would carefully check the main capacitors out, see if heatshrink wrap has shrunk more, showing they need replacement, also check vent plug on undreside of caps for being 'pooked out' meaning replacement is needed. caps look like large cans with a value in mf  or uf, and a voltage rating. never go any smaller in value or voltage. as old as unit is, i would replace the main caps without question. by the way, very nice amp.