Well, today the tach went to zero.
Usually you have to rap the glass with your knuckle, but this quit while driving.

So, I checked for tach generator output.
Nothing.

Ohmmeter checked the generator and tach head, seemingly normal (similar readings on both).

Looking at the breakdowns, I figured the drive plate or tab on the end of the generator.

So, I pulled the generator (more fun).

The tab on the end appeared to be locked.
Oh-oh.
LOTS of effort with a pair of pliers and it did move.
Checked the depth of the drive plate in the head, compared to the generator, odd, seems like the tab MISSED the drive plate.
Grabbed the tab with same pliers and pulled, it popped out, rotated normally with the "cogging" of the fields.

Popped the back off, took out the stator, and pushed the bronze oillite bearing out with my thumb.

Ooops.

Cleaned the housing and the bushing, Lock-Tited it in, lube, re-assembled the generator, re-installed, tach works as before!

Let's see....two drops of Lock-Tite, and a bead of clear silicone sealer....what, fifty cents in parts and that's a push?

are you saying you did not lubricate the insides with 3 in 1 oil?

Ex

Last thing I would ever use on any quality machinery is 3-in-1.

I have a fine machine oil I use, not something that will gum up.
And, I certainly don't want to have to do this again anytime soon!

I did find what a rebuilt tach generator cost, and was rather amazed.