[Amps] FLAKY AL-80A

[Mr. and Mrs. Magoo]

I'm hoping someone can offer a suggestion on a problem I am having with a 
friend's amp.  Initially it refused to turn on-the resistor in the 
step-start circuit was lumpy, discoloured and open so I replaced it and all 
appeared peachy.  I turned the amp on and off several times and it appeared 
cured.

The owner used it for about 10 days and then it quit again so he brought it 
back.  When it failed for him, the resistor got very hot...he removed the 
cover, held down the safety switch and observed it glowing before he shut it 
down!

I checked the resistor and it is fine...it has not changed value.  I did 
remove the relay to check for pitted/arced contacts and re-soldered 
everything.  It works fine right now.  But I am afraid that it really isn't 
cured.

Anyone have any idea about what the REAL culprit might be?  I'd love to send 
this puppy back for good.

73, Bill VE3NH