Have you had someone step on it while you look??
I'm betting something needs beefed up if you don't see anything loose.
EDIT:: Oh, oh. I understand now that I reread. Sorry.
Maybe it's been that way all this time and now you just notice it. I've done that on a few things. How far off is it from side to side?
Forget what I said about having someone step on it
I'm not sure I would have an answer except having to drill a hole and moving the bolt to level it. All depends on how much distance for the new hole is available to drill into after measuring how much you would have to move the bolt.
Are the steps level?? Maybe the coach angle is off. I can't think of anything else.
EDIT again: What is that hanging down in the middle of steps? Maybe the arm that retracts and extends the steps. I don'dt have that on mine.