It could be the syncromesh going out. Its a common thing in transmissions and they wear quick. It could also be the pilot bearing. Mine does this and I am not into costly repairs to have it just go back out in a few months. Try double clutching! It works great for me. When going into 1st gear and it dont wanna go, let clutch back out and push back in and shift. It will get the syncros ligned up again and it should fall into gear. Takes just a second and seems to work on any stickshift with this problem. Oh and it works for the 3rd gear prob too.
89 YJ Islander, AC,PS, 10 inch lift, 32 BFG MT's, sway quick disconnect, rear track bar quick disconnect, 400 watt 12 speaker cd player for tunes,8000lb warn 8274 with 150 ft cable, and a high lift jack.. Lockers, 35's, webber carb and jacobs ignition comming soon.