shifting problems

i have a craftsman model 917.254920 and when i stop it is hard at times to shift out of gear mainly when im in reverse going to a forward gear. i have to rock the mower back and forth to get it out of gear. i also found when i set the brake when it is in gear
(though my brake is going bad and barly stops me) it has tried to move on me. i was woundering if there is a adjustment for the clutch to help release the belt more cause i dont think it is releasing all the way?