Hughes,
Sometime they get some crud inside in the mechanism. To free it up turn it very slowly from full CW to full CCW about 10 times or more. After some of this "exercise" you should start to feel the detent mechanism start giving you some "click" back and it will start to turn better. Then go full CW and back it out the number of clicks to your setting. If unknown, start at 10 and adjust in 2 click increments (while riding) until you get in the ballpark. Cam.