My guess is that the low reading gauge has some resistance in the pivot points, spraying carb cleaner in the bourdon tube probably won't have much effect.

1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy