2008 RMZ250. Showa stock forks. After assembling forks after oil change the rebound damping screw at bottom of fork won't turn at all. This happened on one fork leg, so I did the same oil change on the other fork leg just to make sure I hadn't put something back wrong or over tightened anything.... but same results on both forks. I took the fork apart and checked the rebound screw seperately; turns perfectly. But when installed won't turn. Any help would be greatly appreciated. The forks worked perfectly before the oil change and I don't want to send them off to get looked at if its just a small thing I've overlooked.