I've had that issue twice with mine. Both times it was the inlet check valve. The first time it was leaking I got a kit for it and installed it. The kit does not contain this valve, BTW. While I had it apart I saw a chunk of plastic hung in the valve and removed it. That was probably all that was wrong with it to begin with. Just recently it was leaking very bad from the same place. I ordered another kit and told them to get me the valves too...they didn't. I went ahead and shut the wash down to repair it. I yanked it apart and discovered the plastic cage of the valve was broken and the closest one was in Cincinnatti, two hours away. I didn't have much choice but to drive up there and get it. I installed the new valve, didn't install the kit and all is fine now.
BTW, our old buddy Randy is an expert on these things. He might not be available for a few days though since his is going to the WCA show in Vegas.