Dang AX15 problems

I'm having a wonderful time trying to figure out just how bad this problem is and the exact cause, before I tear into the good ole AX-15. This happens only on inclines. I put it into first gear and as I ease the clutch out, a loud Bang occurs as it pops out of gear and causes the whole jeep to lurch. I have not been able to crawl under yet but just a week ago I had a bunch of work done on the brakes and rear axle (bearings) at undercar. The checked the u joints for me at my request, and proclaimed them to be ok. When da lizard decides to "jump" out of first gear (only one it does this in) I would swear I feel both drive shafts moving. So My question is; could this just be a bent shifter fork? or could it be indicitive of a more serious owie to the old AX-15. One of our members has a GU one that I may go pick up in GA just to be on the safe side. It has done this slam a jama about ten times over the last 4 weeks, only seems to happen when I have to shift to first on an incline. Help oh more knowledgable ones than I.

There are a couple of things it could be. One is a worn rear output bearing. Does it jump out of any other gear? If it doesn't do it except under heavy load, I am guessing the output shaft is moving a little due to pressure from the pitch of the gears.

The only gear it jumps out of is first. It sure would have been nice to learn this sort of stuff while I was racing but the mechanics always said my job was to go fast and get out of their way unless I wanted them to drive the car, LOL. I found an Aamaco place here in town so will give them a call tomorrow and see about taking it in. I am still thinking of getting that one from our member here (wife has ok'd the expenditure as long as she gets a trip to Georgia out of it).It would be nice to have a spare, or put it in while the other is in the shop.

Yes. The AX15 usually lasts a long time. But spare parts are great