If you believe you have an air leak at the main nut seal, you may need to replace the main seal.
For post with the V2 nut, simply purchase a "Re-Use V2 Nut" rebuild kit here and follow the steps in this video.
For posts with the V1 nut, simply purchase a "Replace V1 Nut with V2 Nut" rebuild kit here and follow the steps in this video.
Factory Service options are available, shop here.