My Little Giant TP-15ULST (VCMA-15ULST?) condensate pump runs constantly without pumping down the full reservoir. If I tap vigorously on the top of the pump it seems to "prime" it(though I know it does not require priming. Anyway, it will then work for a few pumping cycles and then go back to running with no pumping. I opened up the pump and saw that the impeller was not connected to the shaft. Does it just connect by friction when water pushes up against it or is it supposed to have a firm connection? If so, what do I do? Glue it?

Electrical Supplies - Little Giant - VCMA-15ULST, 1/50 HP, 65 GPH - Automatic Condensate Removal...