Nerf "CROSSBOLT Crossbow trigger wont release draw string

sorry water gun was tthe closest match

the crossbow works perfectly up to the npoint of firing, when the trigger is pulled the drawstring isnt released completely. My thoughts on it are maybe the drawsting has lost some tension as if i flick it after pull9ing the trigger it fires the dart, or the trigger is being obstructed internally. If anyone has experienced the same fault and repaired said fault i would appreciate thier comments thank you'italic text'bold text