In reading the manual, it says to tighten the large black knob on top and then back it off one half turn. By golly, there is a lot to be said for reading the instructions. Something that most men do not do often. I must be the exception because I read everything. That's because many years ago, before I was married, my buddy and I set out to assemble a combination swing/slide set for the two sons of a lady I was dating. It was for Christmas. Anyway, he and I got to drinking beer and we got the darned thing almost all put together when we notice that the holes along the top rail were not centered along the rail. They were supposed to be on the lower side of the rail and we had them on the upper side. Partly because we hadn't read the instructions and partly because we had consumed waaaaay too much beer. Long story short, we had to disassemble the entire thing and start over. We ran out of beer but we got it together. NOW, I read all paper work. Ha! Sorry for the diatribe.
Ray