The bit that allows it to go backwards and forwards and up and down. Dismantled this some time ago when I was refurbishing it. Thought I could rely on the parts diagram, it's worked before, but not this time. Not at all clear. I know I should have photographed it but I didn't. Any one got anything that might help? Eternally grateful.
Well just been told look on YouTube. Don't know why I never try it until everything else has failed. Kent Bergsma has an excellent series on seat repair.
Here is an old thread that may have some useful photos.
http://www.peachparts.com/shopforum/diesel-discussion/352422-diy-%96-pictorial-w126-front-seat-cushions-w116.html
Many thanks very comprehensive