I took a look at the 2 original tanks this evening after reading the instructions that came with the new tank. It recommends regularly oiling the hand pump slides (I can guarantee I have not oiled them since I have been towing the trailer). After oiling the slides and removing the nozzles on both original tanks, I found one had a nozzle blockage. Not much there, but enough to likely keep it from priming. After reassembly and adding water, both are functional again. But, the new tank pumps the water 2 to 3 times farther than the old ones. So we now have 3 functioning tanks.