I am not sure if it's spring loaded, I don't have the camera with me right now. It's certainly pushed in by the sloped metal thingy visible on the left hand side in the pic (excuse the description, it's not my first language). It might be pushed back in vertical mode via the mechanism in the camera itself. Mamiya Germany was very quick and helpful with the part, maybe Mamiya in the U.S is similar. I would just give them a call (http://www.mamiyaleaf.com/support_USA.asp) I just had a look at the invoice, it doesn't have a part number on it, I can only tell you it was cheap, 7 bucks exc. tax. Best of luck getting one!