My gauge was doing the same thing. Turned out the terminals on the back of the gauge were corroded/rusty and not making good connection. I cleaned with sandpaper and oiled the terminals and now it works perfect.
57 GMC LCF 370 55 John Deere 40-W 59 John Deere 430-W 2000 GMC 4x4 56 John Deere 420-W Pix on Photobucket
