I found myself needing a 2x4 Kallax instead of the 2x2 that I had for my scrapping stash, so I browsed Facebook Marketplace regularly in the hope of finding a bargain nearby, finally I scored a white 2x4 that came with 5 Lekman inserts (4 white which I gave to my daughter and 2 smokey), 1 of the smokey ones was broken at the back (the lady had felt pads on the side that faced the walls, which saved me doing that myself). I contacted Ikea to see if you could get a replacement part and unfortunately you can't so Helmar came to the rescue as I really didn't want to send this to the tip if I could save it.
I grabbed out my Helmar Silicone Adhesive and Sealant and applied it to the break on the parts poking out and the inside.
Note - I would later realise with the way this had to be forced back in place that I should have worn gloves and had some turpentine at the ready to clean up the excess when done.
I don't have photos for the next part as my photography assistant was off in Uni class.
Basically I pulled and pushed at the 2 sections that needed to go back together until I had them together, this is why I overdid it with the Helmar Silicone Adhesive and Sealant, I wanted to ensure some wound up in the break once I had it together. This is also why I should have worn gloves, if you get it on your skin wash immediately.
This is when you need the Turpentine, so you can wipe off the mess you made when trying to get the 2 sections to click back together.
As it's at the back you can't tell it was repaired when it's on the shelf, it is now a perfectly functional Lekman to stash away goodies in.