Technical Car seat won't lock in place

[AnthonyH]

The passenger chair in my GP won't lock into place, it slides up and down, so I got it off today to try and fix it.

The teeth lock in place on one side but not the other, and while in situ this doesn't hold the car in place. The bar is meant to pull up an inch or so, but mine doesn't move enough. I just don't understand the locking mechanism. Anybody got any ideas?

 

[AnthonyH]

The spring mechanism is broken and not fixable. I can now make the seat lock in place, the problem will come when someone accidentally unlocks the seat, because it won't manually lock in place again, so I'll be scrabbling around under the seat again to stop it sliding around. I'll try to think of a more permanent solution to prevent the chair from being unlocked, I can live with it not moving at all.