5-spd pops out of 1st gear

Hey folks. For the 5-speed crowd. My 97 4.0 5-speed (AX-15 ? right?) "pops" out of first gear after a few yards, making for quite a sight. Have been able to start in second around town, but traffic scares me. am I screwed? is it worth fixing/rebuilding? Just go for a whole new rebuilt AX-15? If I go rebuild, any sugg on a build up? Ballpark on cost? I like to tow my vintage Shasta 16-foot camper on occasion. Got a feeling earlier heavy towing, smoky burnouts and such are coming back to haunt me.

Again, to the moderator/filter/declarer of "bad words," my 1969 vintage S-H-A-S-T-A loflyte camper is NOT a swear word, worthy of the ridiculous "dead horse" flogging thing.

popping out of gear is usually a sign of bad input bearing, or another mainshaft bearing.
Can you hear any ugly grinding noises coming from the trasns?
It could also be as simple as a worn shifter, or a bent or worn shift fork.
Not too much you can do to diagnose it without pulling it from the XJ.

Thanx Manche. Yes, I have had a grinding on occasion, but usually in fifth, not first. I kinda figured it is going to require removal, in which case I might as well have it rebuilt. bummer. gotta drive my fuel-hog F-150 for a spell.