We use Happ trackballs on our amusement route everyday. 80% of the time when the Trackball sounds "rough" it is a bad bearing. Replace them all at the same time and keep any good ones you find for spares. Preferred by players of Golden Tee, PGA Tour, Silverstrike, Bags, World Class Bowling & Many More. Easy to Install. Will last a long time in a commercial environment, and even longer in your home.