Here are your parts
Model PAV3300AWW

Here is a service manual
http://www.servicematters.com/m...ibrary/docs/16023083.pdf

Sounds like a "Switch, water level" Item 5 in the "Control panel" section problem.

This switch has a tube that runs down to the bottom of the tub.
As water fills the tub it traps air in the tube.
This air pressure builds up till it reaches the set point of the switch.
The switch then trips.
Removes power from the water valve and advances the timer

So It can be one of three things.
1. Something is blocking the tube so water cannot enter it. Undo it at the switch and blow into it
2. The switch is shot. Put a tube on it of the same internal diameter. Start a fill, blow into the tube. It should not take too much air pressure to stop the filling. If you have to blow hard or it never trips, the switch needs replacing. It is a good idea if it trips to put your tongue on the end of the hose so you trap the pressure in the tube/switch, this will check that the bellows inside the switch is not leaking.
3. There is an air leak in the tubing. Inspect it for cracks or holes also if it has become brittle. Replace it is any of the preceding.
Sometimes they loose the seal at the switch, cutoff half an inch of it and reattach it.