This clock didn't work so I removed it in preparation for installing a JPI FS-450 in that hole.
It's probably the original clock from my F model.
Took the back off just to see what they look like inside and found it's nice and shiny with no corrosion. On a whim, I gave it a squirt of WD-40 and it started working just fine.
I'm guessing the oil had dried out as it sat for 20 years while being disconnected from power and the WD-40 broke things loose.
The previous owner had self installed an iFly GPS and used the clock circuit for power. Then he installed a power switch to the GPS as that circuit is always hot.
Anyway if you want to try it, shoot me $20 to cover shipping and it's yours.