The lever on the side between the seat and the door is the HEIGHT adjustment. IF you cannot see the same 2 bolts in the rear of the seat rails.....on the FLOOR.....as you took out in the front.....then the HEIGHT ADJUSTMENT IS in the way.

Follow along. There are just 4 bolts that hold the w123 seat in the car. The whole seat comes out......wish I had a pic of the thing.....let me look...

Well, here's a pic of 2 blue seats --- different years. There is a bolt is each "corner" of the frame. Sorry, I don't have a better pic. The HEIGHT Adjustment appears to be forward in the right hand seat. I can see the front hole on the seat on the left.

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daw_two
Germantown, TN

Links:
Sold last car --- 05/2012 1984 300D Light Ivory, Red interior
No longer selling Cluster Needles Paint
No longer selling New Old Stock (NOS) parts

Past:
3/2008 1986 300SDL "Coda"
04/2010 1965 190D(c) "Ben"
& many more