Cannonball

I will have several Questions throughout the day, i've finnally got some time to fix all these annoying problems. My Tach quit working after I took it into a shop a few months ago, and after looking at it I found that the wire was frayed and cut somehow right below where it clips into the Distributor. I unfastened the clip with what was left of the wire and twisted it back with the part of the wire that goes to the guages. This still didn't work. I checked for voltage and from where I did my surgery the connection is fine. So where else do I look for a problem with the Tach? I didn't take it back into the shop due to being far away and busy and it's been months so it's kinda too late to take it back in now. If I could get my hands on my chiltons it might eliminate some of these questions but It will be a few days before that. Thanks for everyones input,
Cannonball