FWIW, Craig, the temperature gauge movement is basically identical to the
voltmeter (except for the resistance of the internal heater). When I
started investigating the voltmeter on my Stag, I discovered that the
internal gauge calibration adjustment was so loose that I could move it just
by rapping the gauge on the bench.
And with the gauge reading near the high end of the scale, there is a small
but definite pressure on the adjustment, in the direction that would make
the gauge read lower. There is a fiber washer that helps provide the
friction to hold the adjustment in place, so it's possible that the washer
shrank over time and the adjustment was not that loose when the gauge was
new.
My point being that it is possible your gauge has simply shifted calibration
slightly.
-- Randall
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