My Maralunga /Cassina needs help  

Dear Reader

Please can you inform me how to strip the Maralunga to fix new fabric/upholster (on) it ?

I inherted the three seater (from my deceased sister) and i want to keep it, but it needs very much new covering/upholster

Do you have any drawing or manual so I can see what to do to strip and to reset the three seater Maralunga ? Please
I manged to undo the two sidepeaces, but i cannot undo the backseatpeace from the sitting part.

Please every tip, advice etc more than welcom.
Thanks in advance
Danielle
Amsterdam
The Netherlands