toro 455D deck leveling

Good morning all, I am new to this forum so please be patient with me if I do or say something stupid. The first thing I need help with is , leveling the cut on the mower. The unit is a 1994 Groundsmaster 455 D. The mower was just bought by me and has 3500 hours on it. Everything seems to be in fair shape. I have replaced the wheel bearings on all the ground wheels. The deck is 128" cut front mounted "Bat-Wing" When I cut the right bat-wing seems to cut much lower than the center or left bat-wing. I am about done for the season so I will have time to repair the deck. Thank you...Jim