I have an older Performa that is doing something weird. It will fill just fine, at any level and then stop filling. Then the wash cycle starts, and all is well. That is until about half way through the wash cycle. Then it abruptly stops, and starts to fill again (already full) and overflows and just keeps going. If I manually stop it, and click it one notch, it will still fill. But if I click it two notches, then it begins to drain and run towards the rinse cycle. Neither rinse cycles overflow while filling, no matter what the level is set to.
There are no leaks anywhere inside the cabinet, I have checked.
Could it be the timer mechanism is bad? I have replaced it once, but that time the washer was just dead.
Any advice is appreciated!

**UPDATE***
I have found that I can stop the tub filling again by turning the "Infinite Water Level" knob fully counter-clockwise, to "Mini". After the wash cycle is done, and the water begins to drain, I turned the water level back to "Oversize" for the rinses. This leads me to believe it is either the water level switch (the actual mechanism behind the "Infinite Water Level" knob), or the Tub Air hose, that runs from the bottom of the outer tub to that same control.
Any thoughts?
Thanks!