ya, Generac has updated software to allow for 60 seconds run time before checking output to address ice on slip rings/brushes. seems to have stopped wintertime faults on air cooled. i have never had to replace brushes in a unit...but i have 6 sets on hand. simple to replace. I did sell one set to someone that needed to replace theirs. they did work themselves.
Real field (pun intended) data re. quality of brushes today..... at least what Generac uses in those systems seems robust.
Rgds, D.