80q alternator woes...

[TooManyAudis at aol.com]

I'm having yet another problem with an audi alternator -- seems as though I  
went through 5 or 6 in my 4000 and 4000q days, and at least the second time 
with  my 80q -- got it rebuilt about a year ago.
 
I am well aware that past performance (or lack thereof) is no  guarantee of 
future results, but this is a tiresome game.
 
Anyway, I had said alternator rebuilt about a year ago.  For the past  8 
months, I've had to rev the engine to well above 3000 rpm to get it to start  
charging -- not that big a deal, since I've owned VW's that had the same quirk  -- 
although most got going at 1800 or 2000 rpm.
 
Yesterday, there was no charging to be had.
 
So, is there anything for me to check before removing the alternator from  
it's hidden, nearly-inaccessible perch?  Where does the "exciter wire"  get it's 
juice -- I'd like to check continuity before ripping the alternator  out.  
Anything else to look for?  Voltage Reg?  
 
Thanks,
 
 
Tom
91 200q -- off to the big parts bin in the sky
88 80q -- new suspension rubber bits, but it ain't got no  juice.