Dumb question - calibrating fuel gauge

I got a replacement sending unit as my was pooched. Unfortunately when I installed it, one of the screws was too long and bent the pivot shaft. I straightened it out, put it back in but it reads only 3/4 full when full. Its on a 51 poncho.

Short of trial and error is there any way to calibrate it while its out of the tank ?

There are stops that limit its travel - are these used to set it for full or empty ??

Thanks much !!!

 

take it out, connect the wire and a ground lead, and move the sender thru it's travel, see what the gage says.

The tricky part is seeing what's going on when it's in the tank.