Alan, thanks for the note.  I finally heard from Digital Electronics, 
exactly a month after I wrote to them.  Sent me a letter with some 
suggestions regarding some diagnostic tests --- the results were 
inconclusive.  So I packed the unit up and sent it to them.  They 
charged me $35, said they'd put it through exhaustive tests, but could 
find nothing wrong with it.  Suggested I try a new cable, which I 
already had done.  Not too encouraging I'm afraid.  A power supply 
problem certainly sounds like it would explain things, but would have 
thought their tests would have spotted a bad rectifier.  I think I'll 
write them again with your diagnosis and see what they think of that.  
Thanks to you and the other folks who responded with suggestions.  Hope
I don't wind up with a "multi-buttoned paper weight!"  Bill
--- TriDog 6.0
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