The ice maker on my Kitchen Aid has worked fine for years. Suddenly, it has begun to buildup ice at the lip of the tray where it meets with the door dispenser point. When it dispenses ice the ice is also shaved at times and isn't coming out clean from the unit (clean meaning there is resistance). The unit sounds like it is laboring more than usual just to get ice to the door. Taking the ice tray out of the freezer and removing the ice I could find no resistance in the rotating assembly. The unit still makes crushed ice, but seems to also shave the cubes. What could be wrong?