Search:

see the thread below, basically step into your locker and lightly bounce on the floor of the ski locker fore and aft. Listen for the sound of water squishing below the floor.
...

Thanks for posting this up kojack. I'm still waiting to hear back on the warranty claim. Submitted 8/24 by my dealer, still no answer.

Where did you get the plug/cap? Is there a part number on it?