>Sorry Dennis, I disagree with you here.  I have the original alternator 
>still in my 77 Rabbit.  I replaced the brushes 6 years ago and have never 
>had to touch the bearings.  This alternator has slowly gone from 23 
>Amps output 3 years ago to its current (little pun, there) 10 Amps.  
>
>Obviously the diodes are going and while I could get another diode pack 
>and put it in, I'll probably opt to buy a lifetime warranteed rebuilt 
>unit just so I don't have to go through this again (in another 10 
>years...:) ).   

I say, Okay, so maybe not forever.  After 19 years that alternator owes
nothing.  Vanagons seem to have bearing failures more freqeuntly than other
VW,s.  Probably due to high belt tension needed to drive alternator due to
belt not wraping around engine pulley,  high engine speed also a contributor.
 The windings and main diodes fail very rarely.  This failure is usualy
related to an overload or short circuit condition.  In alternators with under
100K on them, failure to charge at all is usually the brushes or regulator.
 That was my point. Windings can and do breakdown wth age, but this is not
usual cause of failure.  As for your Alternator only putting out 10 amps,
what is the voltage?  This is what is important.  If you are maintaining
13.8volts or so, the unit is stll working perectly and keeping up with the
load.  If unit could only produce 10 amps, it would not be able to keep up
with the fuel pump and ignition system.  Turning on lights would cause
battery to run down.  Hope I clarified my earlier statement.  Please write if
I can be of any further help.
Dennis.