Alternator regulator

got a paris rhone in my 87 carrera. The brushes and regulator are a unit, part of the alternator. Does anybody know how to test the regulator. I have tested the output diodes and they are ok and I know that I can install the reg. in my operating alternator but it is a real pain, pulling the alternator, which is why I want to check the regulator on the bench, so to speak. No urgency here as it is a spare but it is really not a spare unless I know it is ok. Thanks, Val