Please educate me - water level switch function - direct drive Whirlpool washer

[aribert]

I'm a small time landlord and service my appliances. I have never needed to repair any washer related to water level. The washer is a Kenmore 110.88752790 24 inch stacked washer/dryer - in Whirlpool speak, this is the 24inch Thin Twin. When the water level switch is set for a large load, the water fills the entire drum up to the rim - see image. This appears to be several inches too high. This water level is essentially the height of the drum and water leaks out of the drum/rim joint.

What little I think I understand about this switch is that the switch operates on air pressure. Is this true? How does the water level setting work? Is this typically a works till it fails type of a part?

 

[DADoES]

An air tube connects from the side of the outer tub to the water level switch in the console. Rising water in the tub during fill pushes air through the tube into the water level (pressure) switch to flip the contacts in the switch for fill to stop and the motor to turn on. The switch has a spring mechanism that changes the required pressure to trip-over the switch contacts for multiple fill levels per the knob position. Your model appears to have a fully-variable range selection between minimum and maximum on the selector knob.

There typically is an adjustment screw on the switch mechanism. It's factory-set and the screw "sealed" with a bit of locking compound but it can be adjusted if necessary. Loosing the screw to reduce the pressure will lower the fill level.

This parts source has several photos of the switch, you can see the adjustment screw. Adjust it a little at a time, draining and refilling the machine between adjustments to insure it's operating/reading correctly from a tub-empty condition. Set the knob at maximum level when doing the adjustment, the lowest level is according the range of the switch cam.

 

[me]

I'm not familiar with top loaders, but potentially if the pressure switch's air tube, or the air chamber at the bottom if it has one, gets almost blocked with sludge it could restrict and slow the airflow into the pressure switch, so it doesn't keep pace with the rise in water level, allowing it to overfill.