Not sure on how easy the fix it, but it happens a great deal with the ax-5 trans. Its too weak in some cases even for the 4cly. Lots of folks swap in a ax-15 which is mounted behind the 6cly so it can handle the 4cly without issues. Look for a 94 and up as those have the external slave if you decide to swap it.
CJ.XJ.CJ. TJ. TJ.ZJ. TJ.TJ. ZJ.ZJ.YJ. XJ
Depending on how you are using the Jeep you might not have any real need for the 5th gear. If you aren't going to run much over 65 you can readily get by without 5th gear at all.
I think people have a tendency to lug the 4cyl because they don't like to hear the engine sound. Actually, you should get better mileage with the 2.5 running it at 3000 rpm than at 2000 because of lugging it. The bearings will wear less if run faster with less loading.
I find that the first mod to do on a 2.5/5spd is to put tape over that stupid little arrow that tells you to shift about 1000 rpm too soon.
I lost fifth gear sometime ago It can be fixed. But fair warning it is expensive when I last checked it was about 1800 to replace it. I had fifth pined. It's not to bad I don't twist mine much over 2000 rpms.
So I decided to name my jeep Christine, first after my wife second after the Steven King book, sooner or later one or both may kill me!!
I don't have 5th either but I rarely use it anyway. I don't know that I'll fix it knowing that it could happen again. When time and money are abundant.. I'll consider the ax-15 unless there's a way to bullet proof the ax-5.