Are you talking about the removable pins that hold the stairs into the bracket? If not, what part exactly? The quick release pins are available at most chandleries as they are used a lot on sail boats as well as fish boats outriggers, they are not some Marquipt exclusive item. I agree that Utsch's is a good place to ask; we always found them very helpful.
"There's the Right Way, the Wrong Way, and what some guy says he's gotten away with"