I assume you've checked the obvious like wire connections. Our van was trucked from CA to Las Vegas. All fine when it left, but when we got it, the alt. light was flickering. I had visualled the wires, but I should have tugged at the connections. After the seller next-dayed me a replacement alt., as I was changing, I saw the wire had broken inside the shrink tubing -- must have been jostled on the truck ride.
 
Jack
'86 Westfalia Weekender
'05 Jetta TDI Wagon
 

> Date: Wed, 17 Aug 2011 14:02:42 -0700
> From: camping.elliott@GMAIL.COM
> Subject: Intermittent charge
> To: vanagon@GERRY.VANAGON.COM
> 
> Hey all, I'm sending this from a primitive campsite in the Deschutes Nat'l Forest. The last 3 miles to this location the alternator lamp came on and battery voltage (dashmount gauge) dropped. Managed to find a nice spot anyway. After engine cooled, started it to check alt output and it was working again. Have spare regulator, will swap it in. Anything else I might look at? Mrs Squirrel will be joining me tomorrow and could bring things if anyone thinks VR might not be the prob. 
> 
> Sent from my smartphone with tiny screen & even tinier keypad.