you can't. the best you can hope for is that someone will go into a returns dept and beg for you. i bought one of these beds in as-is and it was missing a section of the long rod and corresponding tubes, never have found them again... but at least the bed functions just fine without.
you might want to look on the instructions and pull the item code and list it so that some benevolent soul could ask the next time they are at ikea (and that person could very well be me since i'm there often and currently have about 6 ikea projects working
)
