2002 954 shift problems

I apologize in advance for the long explanation, I just want to be thorough.

Ok, so I was driving off the highway, as I went to downshift, the pedal wouldn’t move, it wouldn’t shift, it felt like the shift pedal was completely locked up. Did a little inspecting, discovered that the gear arm lever connecting the linkage to the shift rod had come loose. I managed to coast home, in 4th gear riding the clutch as needed to take off. The next morning I tightened the gear arm lever and still experienced the problem with not being able to shift down from 3rd or higher. 1st and 2nd have no problems whatsoever.

I then replaced the gear arm lever hoping this would fix it, it didn’t. Now, I experience a false neutral occasionally if I shift to neutral from second and sometimes it will shift all the way to 5th and back down until I get riding. Once I’m riding, I can freely shift 1st, N, and 2nd. But the moment I go into 3rd, I can’t shift down anymore. The pedal locks up and I have to stop, clutch in, and wiggle the pedal up and down with my hand until it moves into place and I can start downshifting. It seems that I can only downshift from 3rd or above if I move the shift pedal up and then back down quickly.

when I get home today, I’m going to mess with the linkage and adjust the clutch cable but I have no idea whatthis could be and really don’t want to go to a shop unless I absolutely need to.

thank you for any responses.