NEED HELP. I have been trying, and trying, and trying to get my tub to prime, but due to what I believe is an air lock, the dang thing won't prime. I have emptied and re-filled three times. Once directly through the filter, once through filter and forcing water through the jets, and once directly into the tub. I have tried using a plunger to force air along. I have loosened two fitting: one before the heat pack and once at the high point entering the pump. Getting to the fitting at the end of the pump will be problematic. The error msg. I am receiving on the button panel reads "dr," which indicates "poor water flow or air bubbles." Nothing works. What am I missing? FYI - The pump is a Waterway Executive 48....the darn thing just makes a 'buzzing' noise for a few seconds, recycles, makes the noise again, and then shuts down for 15 min, and illustrates the "dr" message.