Bernhardt sofa put money on support fall bad internally. Springs OK. Any thinking how to fix the sofa? ...
Answers: I do these repairs professionally.
There is not stock answer as construction methods vary greatly and end points vary. I consider it a problem solving exercise.
Pocket screw and glue blocks are commonly the way to restore structural integrity if it's of late separated joints. Sometimes, the sinuous spring clips hold just popped bad. Sometimes, I have to remove pieces and re-cut from fresh wood and numeral out a way to attach them minus having to unchain and redo profusely of springs and upholstery. I usually leave things stronger than I found them -- replace plywood beside hardwood, replace slats with fabricated I-beams, replace pneumatic nail or staples with screw, etc.
Normally, the best way to find in to hold a look and effect the repair is to remove the dust cover (bottom panel). At that point, it depends on the damage, the construction, what your problem solving knack is and how handy you are.
for a problem like this it is best to hold a professional do it