You can blow the white covers off with compressed air which allows you access to get oil into the lower bearing. Thats the one that sits in moisture. The lower end cap to motor housing TRAPS moisture on the bearinG.
Once you blow the white covers off you'll see a small orifice 9very bottom sides) in which to spray 3 in one oil in there. Spray till you see it dripping out the housing. It won't hurt anything. Do this ea fall and keep them covered when not traveling. Only replaced 1 motor in 14 years since doing this.
I cover with freezer bags and stuff foam packaging blocks to keep the wind from blowing them off during storage.