Around 4-5 months it's so common for the pacifier to become a prop and start to cause more problems than it solves. You'll find loads more info on the 'Props' board, but basically your options are to either continue to replug the pacifier until he can handle it himself, or wean. The two weaning methods are either to go cold turkey, or gradual removal. Personally I never had the patience for gradual removal so for us it was cold turkey and after 3-4 days the dummy was forgotten.