(ET) My my... Mower motor mayhem makes sense

[Chris Zach <czach computer org>]

Ok, I pulled the top of the first motor and sure enough both brushes 
were stuck in their little holders. Popped the brushes out, worked them 
a bit and they were ready to go back in.

The bearing looked fine, so I simply put the top on and voilla: Motor 
works again.

The question though is why do the brushes seem to stick on these mower 
motors? Weather? Lack of use? They were pretty tight in there...

Chris