Called for tech support 3 times in the last 2 days at the "Truck and Car shop" where the Tach is distributed as a CounterParts item and received no return call. Only contact is a order number 1 800-243-8947 where they took my contact info and the nature of my call and said they will give them (tech) the message. In todays interactive world you would think emailing Tech support or even placing a order online would be preferred. I purchased plenty of restoration parts at the GoodGuy's shows from them over the years but the website isn't up to Classics Parts site standard's.
Sorry "oldtrux", I was hoping this helped but I its my problem and I will continue to work on a solution. Coming up I'm installing a clock in the panel so I will have the Tach removed again and will test it as Ray_mcavoy suggested...Joe