hi,
organ doctor, you have it the wrong way round, inside the fuel tank, the sender unit has the main feed with a pipe roughly 4" up, the reserve has the mesh filter at the bottom, to stop all the crud etc from being drawn down the pipe.
the reserve cable on lawrence's car runs down to the back as it is an air-con car, set up with the fuel pump and reserve tap under the tank. there is a spring on your cable to help it return when pushed back in due to it being such a long cable, maybe it has been replaced with too strong a spring pulling it back in without you pushing it.
ian