Well, Im getting through my to-do list slowly. Now its time to sort out the slidy door, which during driving, pops open onto the 2nd catch. The locating pin was too high, causing the lock to sit on the pin, and this is now at the correct height. But looking on BW, there seems to be a plastic piece missing from mine. Is this piece crucial to stopping the door from popping?

After taking of the lock, nothing looks worn, or am I missing something?
Thanks for looking!