My gauge now reads 195 and I'm a happy camper.
Here'* my theory and it'* worth what you paid for it. Ron suggested that I run a jumper from the signal wire to ground and see if it would cause the needle to read full hot. I did this 3 or 4 times and it appears the coil in the gauge just needed a few stretching exercises.
If you have a lazy temp gauge, try grounding the signal wire a few times and see if the accuracy improves. It sure helped mine.
Ron, thanks for identifying the wire colors for me.