Fixing Bosch SHE series insufficient fill issue? (SHE43R Series 300)
It was the fill solenoid, Bosch part #00622058.  My kids and I ran a bucket test, operating the valve into a bucket and timing flow over one minute:



Don't do this at home (ahem), note the bare wires from the scavenged extension cord: it's a 120V solenoid.

Test runs produced 5,8 and then 6 cups of water in one minute with the filter completely removed.  This explains the inconsistent behavior.  The new solenoid from the local parts store produced 12 cups in the same condition.

The hose was grotty also, and is going back to FluidMaster under Warranty: