1995 Ford F150 6 cylinder 4.9L

My temperature gauge on the dash has been stuck on COLD for about a year.
The heater produces hot air no problem.  I changed the thermostat anyway,
but it didn't make any difference. So when my mechanic was doing some other
work on the engine, I asked him to change the temperature sending unit and
check the wires for damage while he had the truck on the lift.. He changed
the temp sending unit and he said the wires looked OK visibly. However the
needle still is stuck on COLD no matter how long I drive it. The engine runs
fine, and there is no evidence of overheating. I would just like to get the
temp gauge to work, so I can monitor things better on this old truck.

I am wondering if there is any electrical connection in the steering column
(clockspring or ignition switch) that could be broken, and cause the temp
gauge needle to malfunction. The reason that I say this, is because there
seems to be a lot of "up and down" play in the steering wheel.

Any insight into what would be a likely cause?

Thanks,

Gary