Michael,
I take your point and agree that Dan's the Man when it comes to dizzy's, however with his advice I took mine completely apart and replaced everything except the sets of metal bushes and it's like new. Dan will probably say that one needs a special machine to test the dizzy advances/retards (051) properly and I have not had this test done. However, my dizzy (051) looks and works superbly. A number of the internal components were damaged and replacing them was quite straight forward and rewarding also. Plus I live in Germany and so shipping it to CAN was not really a swift option.
Bill, I don't have a diagram. However, do a search under distributors and in there somewhere you'll find (a) a ton of information, and (b) a link to a website where a guy rebuilds (more cosmetically that mechanical I think it's fair to say) dizzy's for VWs. His site is useful only because it shows in lots of photos what the dizzys are like when taken apart. I have a load of photos of mine I can send if you email off line and aren't in a hurry (I'm travelling now). I'd say have a go at it. I am glad I did. Just note, though, that to get it tested properly you would need to send it to Dan. What I would definately do is call him and get a rebuild kit from him. He's very helpful. Finally, you don't need a diagram. Just a digital camera and the search function here.
JH