your shift lever bushings are bad, easy fix.
My 1999 Jeep Wrangler also pops out of 1st gear once in awhile. From what I have gathered it could be worn out linkage, a worn out syncronizer & springs, rubber transmission mount, or a worn out 1st gear itself. (Good time to also check the clutch friction disk). I changed out first gear on a British Triumph Sports car years ago, but don't really want to on the jeep .... George B.
check your shifter bushings, next would be inside the trans at the shift collar.
Your synchro is most likely going bad, the same one works for 1st and 2nd so 2nd should be giving you trouble too.
A 1999 Jeep transmission does not have a modulator valve.
You may have shifted into reverse by accident, I've done it a few timesAnswerYou may also be having problems with the synchro rings that allow the gears to mesh without the grinding. 1st-2nd gear share a synchro and 3rd-4th gear share a synchro too. It sounds like the 3rd-4th gear synchro may be worn.
Your main bearing in the trans is going out, 4th and reverse don't use the same shaft. Get it replaced asap Note, this is common to the ax5 transmission, but is normally set off by low trans fluid.
Check your fluid level, low fluid and heat can cause it to stick. You may be able to work it back out of 1st after the lube ids topped off by driving it for a bit, and trying to move the shifter while engine is off.
Synchro's are going bad inside the trans, should only be an issue while moving.
I had the same problem. The plastic spacer inside the shifter handle is slipping past whatever it hits on the bottom side. If you pull up real hard on the top of the tee (the part your palm rests on), you will pull it off and see what I am talking about.
my car is not working in 1st gear
Gear ratio error in 1st gear.