I recommend you dismantle the whole lot, clean it, and reassemble. I hope you can tinker?

1. Unscrew the 2 button-head cap screws that hold the sliding latch in place. There are 2 springs that push the latch by pushing against the button-head screws. Remove the latch but take great care not to lose the 2 little springs. Clean the latch surfaces as well as the surface against which it slides.

2. Unscrew the bolt that adjusts the delrin-covered block and clean the threads.

3. Unscrew the 2 grub screws that hold the springs in place and clean the threads. Apply a medium grade Loctite thread locker (preferably blue Loctite) and replace the grub screws. Ensure they are just below the surface.

4. Apply blue Loctite to the block adjuster bolt and screw it back in with the new block in place.

5a. Apply Loctite to the button-head screws and screw them down, all the way but not very tight, taking great care that the 2 little springs are properly in place. This is very fiddly.

5b. Now carefully unscrew the buttonhead screws a small amount until the latch plate can slide freely. Make very sure the buttonhead screws cannot turn freely after the Loctite has set. Make very sure the latch plate does not bind on one of the buttonhead screws which would cause it to misalign and break the delrin. make very sure the buttonhead screws are not unscrewed more than they have to - this will give the latch plate too much slop.

6. After making very very sure that the screws cannot turn freely (under vibration they will unscrew if they can) and that the latch plate can slide freely without binding, and that the springs push the plate symmetrically, adjust the bolt for correct latch lever tension when closing the handlepost hinge.

So in summary, there are 5 separate screws that all need Loctite and all need to be adjusted perfectly for the latch to work properly. It is important that you understand how the latch works so that you can assemble and adjust it perfectly, your life may depend on it.

It is known in the forums that I find the latch design a scandalous piece of work, but if working properly it should be OK. But even then I won't trust it 100% as there is no fail-safe backup mechanism.