<VV> Clocks: One is Fast, One is Slow

[Mikeamauro at aol.com]

I recently installed two GM NOS clocks. One is in my 67 coupe, located in the 
center of the cluster (this is NOT a Corsa dash)...this clock runs fast; it 
picks up approximately 5-Minutes every 24-hours. The other is a dash-top 
mounted unit, residing in a Greenbrier; this clock looses about 5-minutes every 
24-hours. QUESTION: do either have a "Slower-Faster" adjustment (like most wall 
clocks)?  Or, for at least the fast one, has anyone had success dropping the 
supply voltage through the use of an inline resister?

Thanks in advance for any suggestions offered,
Mike Mauro