ok so i found a knee knocker tach which i believe is an earlier 60s tach, since it has the chrome housing, i removed it from the housing with extra care of course and put in the console of my 67 skylark, im trying to test it before i bolt everything down, i hooked up the blue wire to negative on my coil and tried a chassis ground, to mounting bolts and nothing, all i get is a shock if i touch it any help is appreciated thanks