Thanks blw2 for the note. The back of the sofa is fixed, I cut some 2x3's at an angle and mounted them to the wall under the window. The sofa back screws into those. They are only 1 1/2" on the bottom so they don't interfere much with sleeping.
The rear of the couch seat is hinged so that you can lift it and swing out the piece that makes it into a bed. Then there are 4 support that swing out to support the bed extension (they look they little gates in the picture) - I just used hook and eye bolts to stow them when in "couch" mode.
Larry
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