Thanks all for the feedback much appreciated !
Yes, I am aware of the electronic pins on back of thermostat display and how they all connect to female connectors on back-plate attached to wall.
I have to assume that all is good, but have no way of knowing for sure?
But you all know what 'A-S-S-U-M-E' means !
Thermostat is about 5 yrs old.
Slickcraft.... you said that if thermostat front panel is pulled out, the furnace would shut down ? I have a 2-zone system with another thermostat upstairs. That said, would pulling one thermostat out offline, necessarily shut off the entire furnace system ?
I've always believed "keep it simple', so will start by replacing batteries in thermostat, and go forward from there.....
Will report back with results.
Thanks,
BD