When mine does not work, I use an air compressor line with an air blower wand to pressurize the water in the tank. I open the lid and stick in the wand. I use a towel to seal the top of the tank while holding the trigger. Happens a few times a year.
My buddy bought a 4x4 last fall. After hunting out of it, he thought it was too small. We added 2' walls between the panels to make it into an octagon. We widened his old stand platform and built it on top. Plenty of room inside now.