Its a compound issue on the 01E.
1/2 synchros wear out, causing slightly notchy shifts and perhaps even some grinding if you try to rush it.
However if treated with care it'll remain like that for a long time.
What usually happens though, is at some point, someone goes for a fast 1-2 shift and properly grinds the box. When this happens, it mangles the teeth on the synchro hub, which means the hub will no longer smoothly engage onto each gear.
Sometimes it'll become very stiff to engage, other times it'll get jammed in gear, and other times you'll simply no longer be able to select the affected gear.
Before you condemn everything though, check the linkage alignment. My linkage isnt quite right, and it will often block 1st gear and its like pushing against a brick wall, unless you pull the stick slightly over towards 3rd then try and it drops right in.