Sending unit?

Hey guys was just wondering if any of you have ran into problems with aftermarket sending unit? I bought a new one from classic and it will not go past 1/4 tank Ive had it out and when U move it by hand it reads right I put it in a bucket of water and it does float and move to full Been messing with this thing forever. Its a new tank from classic also, Ive triple checked to make sure its the right one and it is. The arm moves some what freely like I said it works in water. Just seeing if anyone else had problems. I bought it about a year and a half ago and just got it up and running so Im working the bugs out and this is one of them. Thanks Nate

Does it read outside the tank too?Could be your gauge itself or getting stuck in the tank possibly

Is there a way to adjust it? Kinda like the old toilet bowl arm.

No way to adjust, and yes it reads right when out of the tank. Nate

I got to believe if it works out of the tank,there maybe something in the tank restricting it's full movement.Can you put a flex mirror in the tank to make sure the sending unit arm isn't hitting anything?