Sun Distributor machine repair

[Lynn]

So.... I bought this really cool vintage 680Distributor machine. Have not had time to mess with it. But, a really good buddy needs to use one right now (well, within the next few weeks), so I chucked a 480 distributor in it yesterday, and tried it out. I would really like to get it working for him. You can't imagine how much he has helped me out over the years.

Spun up just fine, speed control works perfectly, and it is nice and smooth. So far, so good. Calibrate the dwell meter, and the dwell function works fine. Adjusted the points.

Switch over to RPM and I get nothing. Of course without RPM function, the strobe light indicating advance isn't working either.

I don't want to just throw parts at it. I may end up buying a strobe light, but figure if the RPM isn't working, it probably has no signal to the strobe. I plan to take it apart and see if I can find a problem. But, realistically, figure the problem is internal to a particular component.

Is there a good downloadable repair manual available? I found Paramount (who sells lots of parts and machines). Didn't see a manual, and am guessing he doesn't want to share too much knowledge.

Second choice would be a hard copy manual, but guessing that is almost non-existent.

Lastly, is there someone here, or that you know of, who can point me in the right direction as far as what to look for.

As always, thanks for any help.