Temperature gauge question

["Mike Michels" <mmichels@socal.rr.com>]

Hey list folks:

The temp gauge in my Mk 1A reads at least 25 degrees low. I checked the
instrument voltage regulator and it was feeding 12 volts to the instruments.
Replaced it and verified it was supplying the correct 10 volts. Temperature
reading is better, but still too low, when sender unit is immersed in hot
water and compared with with digital thermometer. Do I suspect the sender unit
or the gauge? And can the gauge be adjusted to calibrate it?

Thanks.