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Replacement parts for General Electric WPRB9220C0WW Washer | AppliancePartsPros.com

I was told that the plastic box on the side of the tub governs the height of the water.Does it need to be cleaned if so how does it come off ?

It does not control the water fill height.
As far as I know it does not come off.

Sounds like a fill assembly (switch pressure Item 10 in Section 1) problem.

This switch is actually a pressure switch. It has a tube that runs down to the bottom of the tub, as water fills the tub, air is trapped in the tube. As the water rises, the air pressure in the tube increases until it reaches the switch's set point then the switch activates turning off the water and starting the agitate.

Possible problems.
1. Gunk blocking water from entering the tube. Remove the tube at the switch and blow into it to clear the plug.
2. Cracks or holes in the tube allowing the air to escape. Inspect the tube. Also check that it is tight on the switch, if not, cut off half an inch and re-seat it.
3. The switch is toast. Get a piece of tubing with the same internal diameter and attach this to the switch. Start a fill, then blow into the tube. You should be able to stop the water flow without blowing very hard.
If you cannot stop it the switch is toast.
It sounds like it does not overfill at lower water level settings so I doubt the above test will tell you anything.
But if the water does not shut off as soon as the switch activates then the water valve may not be closing fast enough. This would be a long shot.

Spo if the tubing is good then I would replace the switch.