I thought that might be the one you need......
.... but you don't actually NEED it
Many years ago my car decided to jam itself into 5th gear whilst I was driving - no problem until i came to a junction and had to slip the clutch like buggery to get to a safe location.
Once at the safe (car park) place I did the 'LEC telephone shuffle' and ended up on the 'phone to Specky who talked me through the procedure you have just undergone...
.. i discovered that the cam had slipped round the shaft and jammed the movement, but all gears were selectable through the big hole in the top of the 'box with a screwdriver - so the 'box was good!
I simply put it all back together with the selector in neutral, and continued the weekend using only 1st -4th gears.....
...except that on the way home I forgot and snuck it into 5th, where it stayed (but I realised whilst still on an open road, so carried on until i got to a layby).
It was a simple job (now I knew how to do it) to remove the cover, but instead of doing the same again I just removed the cam and spring and put it back together.
Everything was fine, and all gears can be selected - just that if you try and go from 5th to 6th there would be a horrible crunching sound and, no doubt, lots of damage
Anyway, the 'temporary, get-me-home repair' was done about 5 years ago, and the cam and spring should still be in the toolbox somewhere
If I can find it, I'll post it up to you.