Just can't win on this deal! I got the new tank pump today and carefully installed it on the sending unit. Before wriggling it into the tank, etc., I thought I'd test run it for a second just to be sure everything was good. Used a jumper from the battery, and the brown ground wire in the harness. No action! So started to check continuity various places. Ends up the only break in continuity is the one inch inside that sealed plastic block on top of the sender mounting bung ; external. The pump runs by jumping to the underside of that block, just inside the tank, on the little soldered post terminal, and the harness is good right to where it disappears into the plastic. What is that thing anyway? Are there components inside it? Is there a field repair I can do, or am I now looking at replacing the otherwise good sending unit? Btw, the old pump was indeed bad when bench tested separately.