An update: Ended up calling a professional to fix the problem. Didn't want to install another major part and then find out that that wasn't the problem. Turns out that a piece of glass (from a glass that broke months before) had found its way to jam the drain impeller. When I tipped the dishwasher to investigate and install a new drain pump and with all the bumping, it must have dislodged into the drain pipe and I couldn't see it. When the dishwasher was back in the normal position, the piece of glass slipped back down and stopped the impeller. The pro just took the botton panel off and took the drain pump off and it was immediate apparent that the glass piece was there (it couldn't hide). Lesson learned - take the drain hose off and make sure nothing is lurking up there!