[rcooled]

Before you go to all the trouble of pulling the generator, first make sure that's the source of whatever problem is occurring and not the regulator.
Here's how to troubleshoot the VW's charging system:
Fault Finding the VW Charging System

Originally Posted by widebody911

You will need a 36mm socket and a way to hold the whole mess while you break the fan loose, and then again while installing it.

You can wrap a piece corrugated cardboard around the body of the generator and hold it in a bench vise. Don't squeeze it too tight. Put the belt pulley back on and put a screwdriver thru the slot and against the screw head on the generator end cap to hold the shaft steady while you loosen the 36mm nut holding the fan on. Be sure to re-tighten that nut to the proper torque value and use a bit of blue Loctite on it. There's also a shim stack between the fan and its mounting flange...don't lose any of 'em during the R&R. Before reinstalling the complete unit back into the shroud, check the orientation of the backing plate assembly...the open slot on the inside piece needs to face down and the generator should be 'clocked' same as it was before (this applies only if the motor has a 'doghouse' oil cooler setup where the cooler lives in a separate housing attached to the rear of the shroud)