I found many sources online for troubleshooting the problem, although not for my model. I Identified that sensor optics were not working properly by using the same principles available for debugging an in-the-door icemaker. The optics emitter and receiver boards needed to be replaced. I ordered the two boards together in one package and they successfully solved the problem. Note that Kitchenaid (for this model) shows the boards in the parts list as included as part of the freezer bin divider assembly (receiver board) and icemaker switch assembly (emitter board). I didn't need those parts, so I just ordered the optics boards specified for other models. They worked fine and I saved about $100 by not having to purchase the plastic parts.