My dishwasher is leaking from the door. Basically a flood of water is overflowing or being forced under the door and over the lip of the bottom basin during the wash cycle. The problem is intermittent. The lower wash arm of this dishwasher makes contact with the Valve Assembly Manifold (W10077903; parts diagram) at the back of the machine when the machine is not running. A repair professional suggested that this may be causing the lower wash arm to get stuck and spray water at/under the door. I'm skeptical because the lower wash arm has plenty of play to clear the Valve Assembly Manifold during operation. In addition, it looks like the machine is designed to lift the lower wash arm with water pressure to allow the arm to spin more freely (and clear the Valve Assembly Manifold). Am I right about this? Before I spend a few $100 on the repair, I want to make sure we've identified the problem correctly.

I've considered the following:

Spray arms are intact and unobstructed
Door seal is intact and clean
Machine is level
Water inlet shuts off correctly
Overflow and microswitch are working

Are there other things that might cause this type of leak. I'm wondering if the machine is overfilling either due to high water pressure, backflow from the pump or a faulty water inlet.

Thanks for any suggestions or ideas!