How do you unfold a futon transmission.?

I'm assembling a mexican futon(sofa+couch) and the instructions asks to unfold the two transmissions.

I can only extend them to a v shape like the top transmission in the link below.

I'm supposed to extend them like the one with the letters below but can't.

http://www.futons.net/browseproducts/Futon-Hinges-Set-(Triple-Click).html

Do you have any scrap wood around to screw to them? Doing this would make it easier to flatten them.

Can a futon mattress be steam cleaned?

My carpet steam cleaner has a hand tool attachment for cleaning upholstery. I cannot find a tag on the futon mattress though to see if it says "S" or "W" though.

Yes you can steam clean this, but you really need to make sure that you don't get it soaked. IF you get it to wet then it will dry on the outside and not on the inside and you could have the possibility of it molding on the inside.
Make sure you use just enough water to penetrate the material, then I might suggest hanging it out side to dry.