Mike in Utah

Hi,

I have a Datsun 610 and the fuel tank got a small hole in it. No problem as I took it out and had it repaired. But...when I reinstalled the fuel gauge sending unit it doesn't read the tank properly. When the tank is half full it reads it as 3/4 full. I took the sending unit out again and moved it by hand and the gauge registers as it should. So what am I doing wrong?

Thanks ...