No disrespect is intended towards trebor in this post, but unfortunately
the current 'how to' has actually missed the real cause of the fault with the rear seats becoming stuck or failing to latch, and instead attempts to rectify it by altering the angle of the plastic release button.
The real cause of the fault can actually be seen in the photos in the how-to posted by trebor. The metal loop which rather cleverly forms both the catch and a spring has jumped out of its housing. Meaning it no longer acts a spring and the plastic release catch misses it as it has now moved slightly further over.
trebor's current fix may enable the release catch to engage with the metal loop once again, but doesn't fix it fully because owing to the way the bar is formed it will only act as a spring when it is constrained within the plastic housing. Meaning it may not work with the body-mounted striker (hook) properly.
You can actually see in trebor's photos how it has jumped out, and how it should actually look in these photos below:
Trebor's original photo, which I have altered the captions on:
How mine also looked once I removed it:
How it should be once you pull it back in with force:
Video of it being pulled back in, you can hear it jump in to place:
Moving the angle of the plastic release catch is the wrong approach. Technically all you actually need to do is pull the metal loop back in to the plastic holder as in the above video. It will then line up with the plastic release catch again and act as a spring once more. However, obviously this can still jump out as it did the first time, so to fix it permanently I have come up with the following, which can be made fairly easily at home with only basic tools and supplies.
You need:
2mm thick sheet of aluminium cut into two pieces as shown in the diagram below (some fettling with a file may be required).
100mm length (approx) of 6mm diameter PTFE rod (available on ebay).
Once you've cut two of these out of the aluminium, hold it in a vice and hammer the tabs on one piece down, and the two on the other piece up to form left and right hand pieces.
Cut a piece of the 6mm diameter PTFE rod to length so it fits between the two tabs like this:
Assemble the hole thing and then drill 2x 4mm holes straight through the aluminium and plastic as shown below, and pop-rivet it to the plastic housing using the same 4mm x 10mm rivets that the rest of the pieces use when it comes to refitting it in to the seat.
The metal bar is now constrained inside the housing by the PTFE rod (which is self-lubricating), and it can no longer jump out. The PTFE is held in by the aluminium and also helps to prevent the plastic housing from opening up anyway by reinforcing it.
You do not need to move the plastic release catch as shown in the current how-to which only overcomes half the problem.
Do the other side the same, so you end up with this, and no matter how hard you hit them down on their metal loops, it cannot jump out:
