3rd/4th gear binding seems to be a common problem with EA81 manual trannies (at least the 4wd ones). Same has happened on my 86 Brat. I have a spare tranny I am planning on swapping in. In the meantime, when it locks up, I just shut the engine down (AFTER stopping), shift it out of gear, then restart. Sometimes it doesn't want to shift into gear after restarting so then I shut down, place in first gear, start engine with clutch depressed. Car bucks at start but it seems to free up the tranny.