I'm thinking it is not the Venture gearbox but the crown gear in the top of the leg itself. Verify this after taking the weight off the leg & removing the gearbox from the leg. The gearbox will run if OK.
Been there. Fixed that. Replacement parts are not expensive. I even carry a spare at all times now.
Jacking & blocking is not hard. Chock the wheels well. Jack it. Backup block it. Block the pinbox in the truck even if you want to feel that much safer.
The crown gear can be replaced with the leg still mounted but usually it is a whole lot easier & less time to take the whole leg out & work on it outside. The crown gear can be found in many RV supply stores.
Doing it for the first time will take a few hours as you fudge around abit with it but experienced hands with the right tools handy should do it in an hour. It is a simple job that is good to know how to do.
Boat: 32' 1996 Albin 32+2, single Cummins 315hp
40+ night per year overnighter
2007 Alpenlite 34RLR
2006 Chevy 3500 LT, CC,LB 6.6L Diesel
Ham Radio: VP9KL, IRLP node 7995