Hello All,
I just wanted to share this small mood I did.
I find the tach in a swap meet for
$3USD (YES THREE US DOLLARS, ONE, TWO, THREE BUCKS!!), it had tons of rust everywhere, LIKE A BOAT ANCHOR, ready to go to the garbage. It turns out it only required some love and patience.
I also installed a volt meter from ebay to check the battery voltage (~$2USD) and laser cut a tach base I designed.
Now is rocking like new in my CB550.

Josh