I thoroughly cleaned out sump, impeller, and housing around impeller. Replaced housing and filters. With wash arm off, the pump would produce a column of water almost as high as the top of the inside of the cabinet. After about five seconds the column of water dwindled and completely dropped off to nothing. I removed the filters and housing again to make sure the impeller was not plugged and was actually turning. Would a bad o-ring between the recirculation side and discharge side of the pump cause this problem? There were also chunks of a plasticized material in the sump discharge filter basket when I first took the filters out. Is there a sealant or caulking applied to the impeller housing at the factory? Or is there supposed to be more to the impeller than the radial wheel? I did not know if this material was from with in the machine or something the tenant put in the machine.

Hi,
This would serve as a hunch. I imagine something fell on the heating element, melted and dripped into the water infiltrating your circulation. Plastic utensils are often the source of this type of debris.
Good luck.
Nic.