ok here goes I just got a new tach and hooked the wires like it said (black to a good eng. ground , white to the panel lights,red to 12v switch on fuse panel, then green to the neg. on the coil ) well when I turn the key I can see the gauge move a little but no working tach. took the tach apart and started the blazer and tested the tach board and they all have power do you think it is the gauge or is there another way with a stock ignition set up to hook it up or just take it back and try a new one?????