RE: Eletronic engine syncronizer **SUPPORT **
The minimum rpm the twinsync will display I think is either 1500 or 900. Take the plug out of the engine and try it again.
I can mail you replacement diodes. They really only protect from spark noise with gas engines. If you are running on glow engines then they are not needed at all.
Static or plugging something in backwards can damage them. The other possability is if they were installed backwards. I have seen a couple that this happened on but I beat up the assembly people and put a test in the test procedure to check for that so I doubt that is the case.