Over 12+ years & 15 - 20K miles, I put 7 to 10 sets of starter brushes in my Foreman 400, Armature was pitted real bad once, rebuild shop said I needed a new one, that the old would not last, Well I just went home and thought " what the hello, ain't got nothing to loss", chucked in my drill press, took a file & got the worst, then sand paper slicked it up. Sold it when I bought a new Rancher, starter was still workin... Last time I saw the buyer, he said engine locked up, starter was still workin, he just had put in more new brush set, when it locked up..