you take the spring out pay attention to what color spring comes off the posts some times there diferent. then pull the brush out and unsolder it, it doesnt matter wich way it goes in as long as its a new set of brushes. then solder the new brush in like the old one was when you pull the brush out for cleaning make sure it goes in the same way because thats the way it was broke in. if you pay attention to the brush shunt you will see that it is in one coner of the brush thats how you can tell what way to put it back in once taken out.