we had this issue last year.
We took the camper back to the dealer and they fixed the step, and it broke again 2 trips later when my wife stepped on it.
We went to Home depot and got a grade 8 bolt and washers like Chewie suggested, but we also noticed that the a couple of the bolts that attaches the entire stairs to the camper where loose so we tightened those up. Since then (4 more 2/3 days trips) we haven't hand any issues (knock on wood).
2006 Flagstaff 831FKSS
2005 Dodge Ram 2500 SLT 5.9L Turbo Diesel Quad Cab
1 - DH (me); 1 - DW (Tee); 1 - DS (Jarod, 12)
Nights Camping: 2010 - 15; 2011 - 7; 2012 - 9