Dan---I left out step #1. Disconnect the tach cable knurled nut behind
the tach and pull it out a few inches. Carefully lower it to a working
position and pull it all the way out of its outer sheath. If it's not
broken, you should see the square drive at the other end.
These cables usually start to hum before they break, and can then cause
the tach needle to bounce around, especially at the lower rpms.
If the cable is intact, do the drill motor thingy in my previous post.
If the tach needle spins, then you'll need to look behind the inspection
plate at the distributor drive to see if the nylon drive gear is in mesh
with its drive gear. Let's hope these two gears are still good, as the
last time I checked, they were unavailable from the Big Three.
Dick
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