Tach connection

[TomM]

Thanks to all the input I was able to solve the problem. It was indeed a broken ground wire - see attached picture. Put new terminal on it and reconnected to the mag and the tach works again.

My plane is too old to have the rear access panel, but it is on my list of things to add. I can get through one more annual before the mags need to be removed for the 500 hour AD and I already talked to my mechanic at the last annual to be prepared to install the rear access. He said "Gladly!"

The value of this form is amazing, thanks again for all the input!!!