fuel gage stuck on full

[blane]

I have a 99 cc drw that the fuel gage is stuck on full. I ran it really low and filled it up and now it is stuck. I read to put a 10 ohm resistor to get it to go to empty buy that did not work. The resistor I used was a 1/4 watt. is that wrong? How can I test the sending unit, it does not look bad? There is a groove where the contact rubs the sending unit. I don't want to drill a hole in the tank( for a universal sending unit sinc ehte OEM replacement is so expensive) and it still not work.