Photos or diagrams of reverse lockout parts for GTI(?) transmission?

[OttoKad]

Hello, I recently bought a BX in the USA, and it's quite rough and needs some fixing! It's 19 TZI, and was swapped from automatic to manual from a GTI(?) at some point long ago in its life, and the transmission definitely has a couple quirks, but for now just focused on one thing:

I am trying to figure out what I'm missing to get the reverse lockout working, because 5th gear is very sloppy and doesn't like to return into neutral before grinding on reverse a little bit unless you move it a certain way. I've already addressed the spindle bushings under the shifter boots. While I know the actual issue with 5th gear lies elsewhere, does anyone have a better source for parts diagrams, or able to get a photo of what's underneath their shifter boots for the reverse lock-out? I potentially want to design and 3D print something if the part is hard to find, but I have no clue how its supposed to work and am hoping someone can be of some assistance lol

[Jaba]

There were two types of gearbox fitted to the BX. If your gearbox has the 5th gear directly above reverse then there is no reverse selection lock. The early boxes had reverse at the top left hand position and had a selection lock on the gear lever as pictured in your post.
Which type do you have?

[OttoKad]

Huh interesting. Mine has reverse below 5th, but has the spring collar on the lever, it just doesn't connect to anything.

[Jaba]

Yes you've got the wrong lever fitted there. You also might have wrong gearbox shift links too I suppose. Try removing the 5 gear link (the ball joints should not have play) and manually select and deselect 5th gear. If it feels vague compared to other gears then you can remove the end cover and see the 5th gear and selection mechanism to see what has gone wrong.