Tachometer Problems

[Hack71]

Bought a tachometer with vacuum gauge conversion kit from Classic Industries. I have stock electronic ignition from a newer vehicle, Classic Industries stated it would not work with electronic ignition. I though that didn't sound write as I remember running many tachs on breaker point ignition then switching to electronic with no problem. I checked around and everyone I talked to said it should work, some people said there was a filter to take out some of the electronic "noise" and make the tach more accurate. Installed the tach and vac gauge and they looked and worked great, for 500 miles about 3 weeks, I smelled something hot amp gauge spiked up and tach quite working. I looked over all electrical tach and truck and found no problems other than the tach that quit working. I figured it was a bad tach or it simply burned out. I installed another new tach drove for about 2 weeks and 800 miles and same thing happened. I double checked all electrical and grounds and found nothing wrong other than the tach not working.
I don't want to buy another tach and have the same result, I don't want to go back to breaker point ignition either.
Any Ideas I want to retain the factory look of the dash, I use the tach simply for looks I do not use it for anything else, but I would like it to work.