Fuel Gauge ... Help again!

[Stingray42]

Hey guys, I know there have been lots of threads on this, but i cant find any info to help me! My gas guage isnt working. Before it was at the 3oclock position (bad ground i believe?) and i took everything apart, cleaned up the terminals, the bolts on the back, resistor, etc. i put the guage back in, and the needle (which i had moved the needle when i was cleaning it) and the needle moved a bit, then stopped. I moved the needle by hand, and it stays where i put it. How do i check that the guage is working right, (grounding out guage?) that the sending unit (at the guage back (three prongs) ) is gettign the right power (what terminals do i check and for what?) etcetcetc.....

thanks