Dash temperature gauge calibration

My low running temps were solved with a new thermostat. Before my cruising temps were at 165, and now at 183'. Other issues made me replace the LH fan temp switch, and ECU temp sender.

My dash temp gauge was reading very low, so I also replaced the gauge sender. Unfortunately, this did not resolve my low readings.

My Porsche has a tiny calibration screw on the back side and wonder if anyone knows if the 355 is able to be calibrated?