W124 cabriolet seat squab

[CRJ343]

Can anyone offer tips in restoring the seat squab (bottom) on my W124 Cabriolet. The leather is in good condition but the rear part of the seat feels rock hard

 

[WDB124066]

The spring box may have collapsed. They are not known to be strong on the 124. Item 8 in the picture.

 

[bolide]

Squabs are available new on eBay Germany

Nick Froome
the independent Mercedes Estate specialists

 

[CRJ343]

I gather I need to pull the seat back adjuster knob off the seat back. The "book" says I have to replace them. Is this true or is there a knack to removing them without breaking whatever breaks ?