HELP, drive a 2006 450 Yamaha Kodiak ,bought it used no manual , I switch to 4wd diff lock I can hear the servo turn but if I proceed the machine starts to run rough and sputter, runs good in 2wd , can't put my finger on it, anyone out has experience with this kind of problem, my guess is electrical but really have no idea, any help is appreciated, thnx.....