Tachometer Quit
 

After an indie replaced ignition switch and tumbler, tach started filckering until finally died; car is a 126 420 V8; already tried the ground cable from ground connection behind instrument panel to solid metal screw in instrument cluster; as a matter of fact I tried several screws behind instrument cluster to no avail. Sometimes at freeway speeds if a sidewind hits the car, tach tries to wake up which tells me there is a loose connection somewhere. Can someone tell me how to trace the tachometer cable(connection) from source in engine (where in the block) to instrument panel? I'm terrible at reading wiring diagrams.