My Quota tach "works", but the low number is now ~700 rpms vs. 0. And who knows if it is off by 700 all the way up (like is an indicated 5000 rpm really 4300? or 4500? or 5000?). I was thinking of rigging something up to test, I know idle is way off.
I did a bit of looking for a replacement and found some tachs that I think would work and fit in the hole in the dash ... but they don't say Moto Guzzi, no eagle emblem on the face. They were around $150 and about that I time I started thinking it really doesn't matter.

Would you be interested in that? Or are you looking for an OEM replacement?