Searching for a terrible smell for quite some time. Checked sump, it is not clogged. Drain line and sewer lined draining fine. Finally removed piston and nut assembly, and .....almost vomited. Terrible smell for the assembly and the body valve and check assembly it fits into. Put a paper towel in there and pulled up tons of nasty food, smelling awful. I flushed it as much as possible and reinstalled the piston and nut assembly. Now do I need to replace just the piston and nut assembly, or the body valve and check assembly as well? I assume the second fix requires removing the washer from the cabinet.

Oops model number GSD4020Z05BB