Fuel gauge problem/question

[Copper116]

The fuel gauge in my 72 K5 Blazer was never working right... So I pulled the tank, replaced the sending unit with a new one, installed a new fuel gauge wire lead to the fuse box, made sure the ground was clean and lubed and the fuel gauge still only moves a bit off 1/4 tank.
I checked for power at the fuse box power lug with just a tester light so far and it barely lit up the tester light. I pulled power from another 12v source on the fuse panel for the sending unit and the gauge went to full but back to 1/4 tank when I cut power.
I did replace the resistor on the back of the instrument panel with one (used one) off another cluster I had... and it worked for a while but now it's back to 1/4 tank even though we put in enough gas that should bring it well over 1/2 tank.


ANY IDEAS TO HELP CORRECT THIS PROBLEM WOULD BE APPRECIATED !! THANKS.