Joey Mack

Greetings. I am new to the group and had a question regarding my Tachometer. It is on a 2005 Mack Granit CV713 Dump Truck. I had the instrument trim out today to repair a crack in it. While I had the cover out I decided to wipe down the gauges. I moved the Tach needle out of position. After repositioning the needle back to where it should be I start the truck up and the needle points downward. While the truck is running I moved the needle with my finger to 650 RPM's. When I press on the accelerator the Tach responds normal. When I turn the truck off it goes straight down to the six o'clock position. Than when I start the truck back up the needle does not move. Is there a way to reset the electronic Tachometer?