I gave up. My attempts to resolve this with the retailer Saltwater Aquarium were fruitless and I tossed it in my parts bin. My pump worked fine for a couple of months then started the wobble. I could not see anything materially wrong with pump.
When this started, I just assumed the pump needed cleaning but after cleaning and during the reassembly process, I noticed that it was neigh impossible to seat the upper pump housing on the impellor as the impellor shaft wouldn't stay centered. I seared the top portion by manually holding the impellor in place long enough to seat it in the top bushing.
