I can't see anything wrong in the pics. Does the lever still have strong tension against the bracket where the holes or notches are? I think you're going to need to remove the wheel to see what's going on.
The right front wheel on my exmark did this when I first got it. I had to take it all apart and rebend the lever in order to get enough tension to hold the pin in the lever in the holes in the bracket.
#5
FloGro
Take that adjustment lever and just bend it in, it will be even stronger then before