Fuel Gauge Problem with My '83 C10

I've had my 83 C10 for about 4 years now. The fuel gauge needle has always set on 1/4 tank. I drive it daily and fill it up once a week. I finally got around to pulling the gauge out of the dash. Depending on the way I hold the gauge in my hand, the needle moves. Does this mean the gauge is bad? I checked the contacts on the back of the gauge and they look fine. Any hints on how I could test the gauge would be greatly appreciated.

Thanks,

Brandon (83 C10)

test the sending unit first. test it for OHMS. check it when you know the tank is low and full. i believe the reading for that sending unit is 0 ohms full 80 ohms empty but it may be the opposite. if you want the gauge rebuilt. google John Wolfe they are in OHIO and are the best at rebuilding and resetting gauges.