Here’s what I’ve done (and not):

1. Checked the basics to make sure there is no debris, etc.
2. Checked the black check valve to make sure it didn’t break off and clog anything.
3. Replaced drain pump.
4. Removed both sections of drain hose and ran water through them to make extra sure there was no blockage.
5. I have NOT inspected or replaced the drain impeller.

Here’s the part I can’t figure out:

Everything seems to be attempting to work properly. I noticed the drain hose runs from the pump, under the machine a short distance, then runs up the side of the machine where it’s run through a plastic bracket such that it makes a partial loop, then back under the machine and out the back where it connects to a separate section of drain hose that is connected to my disposer. Out of curiosity, I pulled the drain hose out of the “loop” bracket on the side and pulled the entire length out from under the front of the machine. I then stuck the end of the hose out a low kitchen window (almost 3 ft. off the floor) and ran the machine on “rinse“ until the bottom/basin filled with water. I then used the cancel/drain function. It drained! Not “powerful” but decent flow (like a water hose on “medium-low” pressure). Hmmm.

I then re-ran the hose as originally set up (under the machine, back through the “side bracket” making the partial loop, out the back, to the disposer). Repeat rinse cycle and cancel/drain ... no drainage at all. Water never even made it to the second section of drain hose that connects to the disposer. WTH?

Seems pretty obvious the drain pump works (as did the old one, I suspect), and the thing is capable of draining. Just seems like maybe the pressure isn’t powerful enough to push water up through the “loop” (even though it was able to push it up almost 3 ft to the kitchen window—albeit in a straight line, not through a “loop”).

Any ideas? Is there something (maybe the “impeller”) that could be affecting the pump pressure?