Before you send the gage out for repair, there is a possibility that the calibration resistor is bad. It’s that white ceramic block on the backside. The gage doesn’t quite act like a bad resistor but worth a shot. Find something like a late 70s pick-up truck with a temp gage and take one off of it. They are all pretty much the same.
There are places that repair gages but I don’t have a link with me right now.
There are places that repair gages but I don’t have a link with me right now.