How to fix 66 Cuda Tach?

Kevin74 said
I’m working on a 66 Cuda, where the tach sending unit is remote, behind the drivers kick panel.
I started my debug adventure with a new RTE sending unit. The sending unit works great, it’s output voltage increases with engine RPM, but the tach is still dead.
So now I removed the tach from the dash, and tried applying a 1.5V battery across the two tach terminals, but still no needle movement.
Just wondering if anyone has experience with opening the guts of the tach? I see that Classic Industries has new tachs for $250, but it would be nice to fix the old one
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Never do this, but now that you have, sounds like the tach meter is dead. For fun you might try your ohmeter across the two same terminals. It's possible you burned out the meter, or that it was already open or otherwise "problem"