When I got my Beetle back together I had to change the dynamo 4 times! The one it came with was faulty so I fitted a spare that I had. That didn't work either so got one off a mate which also didn't bloody work! Was fed up by this point so bought an alternator conversion kit! I had to take off the bracket the decklid hinges bolt to to get the fan housing high enough to get the fan out but by the 4th time I was quite good at it! The fan nut I used an impact gun to undo.