Driving a thermometer dial with a servo?

[Tom_G_2010]

I managed to pick up a pair of after market Cessna wing root air vents and the Cessna outside air temp thermometer that mounts in the pilots side vent.





I want to get the thermometer to show the outside air temp as indicated by FSX.  Haven't checked for an FSUIPC offset, but I'm sure it exists.  I hope 

The bigger question is how best to hack the back off the thermometer to retrofit a servo.  It has a temp probe that's a bit less than 1/8" in diameter and about 6" long.  Has anyone ever cut into one like this before?  Wondering (before I cut up the one I have) if anyone knows the basic mechanism.  It would be great if I could connect a servo with the least amount of hacking up the back of it.  Wondering if the mechanism is some sort of by metal that twists or tensions and how it's motion converts to the rotational motion of the thermometer.

Thanks!
Tom G.