That might explain making a sound when it is spinning with no water in it and no change in tempo. I kind of feel like the pump has a small amount of damage and is making a sound when empty that can be picked up with the stehoscope kinda like a grinding sound which transferrs to the back maybe through a recirculation hose. I think we are on to something here. I just can't remember ever hearing one do this. This makes me think the pump has some damage.pump sucking in air
Right now, this thing works like a charm, just has that sound in it.
Thanks.