Calibrating a vintage thermometer?

[35k0]

I have dome some internet research and am still not sure if this is possible, but I want to buy this old thermometer for the sauna I am building.
I am waiting for the seller to get back to me on whether it is stuck or if it still fluctuates at incorrect temps.
Assuming it still fluctuates, but at the wrong temps, can this type of thermometer be calibrated?
I would even consider replacing the thermometer and needle, but I think finding one in that range may be difficult?

 

[Marsim]

There's usually a set screw in the slit on the back that allows you to adjust it. Can't tell from the pic if that one has it or not

 

[engineer2]

On a bimetal thermometers the center post can often be turned for calibration. On others you move the number dial (probably not on this one). Worst case would be to pull the needle and put it back on in the right place (a PITA).
It's best to calibrate it for the middle of the temperature range you plan to use.
Run your sauna to its normal temperature, say 170°F. Give it time to stabilize.
Put your thermometer and the probe for a digital BBQ thermometer (the kind with the probe on a wire) next to each other in the sauna. Give it 10 minutes to stabilize. Best to keep the thermometer electronics outside the sauna.
Turn the adjustment until it matches the digital thermometer. Might need gloves to hold it. Re-check/re-adjust as needed.