Has anybody had any experience with these?

The missus has one and the fuel pump shit itself and was replaced by a mobile mechanic.

After that, the fuel gauge refuses to work properly.

The mechanic raised the float/sender up and down by hand and we watched the needle go from full to empty (the fuel light came on), but when the pump is refitted to the tank and the tank filled, the guage only goes to 3/4 full. Its done this for the past 3 tankfulls.

The mechanic went to holden to order a new sender/float assembly only to be told that its a common problem and there is a trick to fix it, as putting a new unit in will just do the same thing.

Anybody know what this trick is? The holden dealer this mechanic went to seems to be withholding info.

Cheers