I put 2x4's under the front washer feet to get access to screws attaching the lower panel. I felt high vibration on the pump during the spin cycle, so I figured the impeller was damaged. I ordered a replacement pump, and considered just keeping it in reserve while I tried to repair the old pump, but decided to minimize the chance for leaks by installing the new pump. It slides to the right easily if you pry the retaining tab up with a wide bladed screwdriver. The discharge hose clamp was crimped on, so I cut it off and replaced with a screw on hose clamp. I guess I wasn't careful enough making sure the clamp was properly aligned, because it leaked. I had to remove the new pump and realign the clamp. Then everything worked like a charm. No noise and no more codes.
I did open up the old pump, and found an women's underwear waist band wrapped around the impeller along with fabric jammed between a pair of impellers. I don't know what happened to the rest of the garment; presumably it made it through the discharge line. I suppose I could have reassembled and reused the old pump, but I've got a feeling that I would have had casing leakage problems. If you've got the time and patience, it might be worth a try. My pump to motor joint was held together by slotted teeth, and the fit was pretty tight, so reassembly might have been difficult.