There seems to be a lack of clarification around this so I want to say that it has been my experience that it is the electric motor portion that is most apt to sieze. It is in the lower bearing on the electric motor inside the white cup or covers. This bearing and design (how the steel motor housing is dished under the bearing)is where the problem lies sitting in an area where condensation pools and collects.
This is why it is important to cover ea. motor for winter storage.
Twice ea. yr. I remove the white cups and spray a bit of 3in1 oil into the elect. motor weep hole at the bearing bottom and then using a shop vac suck the white cups back into place.