Thank you sir! I went through the major ordeal of getting it out today. What a friggin job!!! It's a 20 year old VDO and has always worked well until I had that Voltage rectifier issue. May have had a voltage spike that messed it up a bit.

I was doing some research a little bit ago and found a Technical Bulletin dated Aug 03 with the description 'ERRATIC OPERATION' it says to add a diode in line of the ignition lead. The diode is #1N4005 Luckily, (which is not in my usual day), I had one in a box!! I built test computers for FA-18 Hornets, that went on aircraft carriers, many years ago and as the average guy....always had a few spare components in my electronics stash. Score one for me!!

I'll get it soldered together tonight and hopefully it will cure the problem. Much cheaper than buying a new tach.

I will most likely get a digital as you suggested. I have seen this advice several times over the years.