Attached is the seal replacement instructions. You could see if a local company that repairs hydraulic equipment or jacks can repair it for you. Try this first though. Extend the jack all the way, clean the lip seal on the jack with a nylon brush. Ger a spray can of silicone with the small nozzle. Work the nozzle under the lip seal. Spray the silicone under the lip seal, move then lip seal all the way around under the lip seal until the dirt stops coming out. Wipe off the shaft and spray it with silicone. Retract the jacks, extend to jacks all the way again, wipe of the shaft and spray with silicone again. One of my rear jacks started leaking a couple of years ago and I did that, hasn't leaked since. You may need to do it more them once. Hope it works for you. I occasionally extend the jacks all the way, clean and spray with silicone.
1999 35 ft. Dolphin 5350, F53, Banks System, 5 Stars Tune, Air Lift Air Bags, Koni Shocks, Blue OX TruCenter, TigerTrak track bars F&R, Roadmaster 1-3/4" rear auxiliary sway bar, 2004 F450 Lariat Pickup 6.0 Diesel Crew Cab DRW, 4X4, GVWR 15,000, Front GAWR 6,000, Rear GAWR 11,000, GCWR 26,000, 1994 36ft Avion 5er, GVWR 13,700, 2,740 Pin Weight.