Slid machine out from under counter, unplugged, tipped unit on its face and removed the pump assembly from the motor (two large hose clamps secure the pump). Found the stainless steel impeller that chops and food before it enters the drain/pump had broken off its drive shaft. Ordered a new impeller/seal assembly, installed it (the only tricky part was the assembly cover was left-hand threads, but you could see that if you looked closely at the threads that were exposed), installed the new parts, and it all works great, now.