I have a two year old(roughly) 6101 that quit working. No alarm sounded. I took it apart for cleaning as per the instructions here on this site and in the manual. The impeller is not siezed. It looks like to me the inner rotor bearing is a bit worn but I'm no expert. Can this cause it to just quit? Something else I'm missing? Can you give me some advice? Order part? Return for a check up? Thanks