Noise during initial drain, washer runs ok

Dishwasher is a SHU3306UC/U12.

It ran great for years, then it started to leave water in the base. Opened, cleared impeller (had some crap in it) and resumed working. Now though it makes a noise that I think is when it is cycling between putting in new water and draining old.

Had the thing out last night, checked every hose, checked sump/drain/impeller and don’t think there’s any residue in any of those. I can’t tell if the sound is coming from the plastic maze on the left (the assembly where the float-switch is).

Any pointers?