1972 350sl soft top will not disengage
 

Just purchased a 1972 350sl. (450). Came with no manuals. I am not able to lower the soft top. The lever will not disengage the pin by the trunk. Is there a special combination with the lever behind the drivers seat to unlock it? Fortunately I do have the handles to unlock the pins on the windshield. If it will not unlock how do I access the compartment to release it?

This link shows the procedure.
Mercedes Benz R107 Hard And Soft Top Instructions - Mercedes-Benz Forum

you may have to get creative, there is a linkage on the lever that actuates a small hook away from the frame pin. this linkage can fail, stretch and sometimes break.
If I recall correctly the lever moves the hook to the passenger side .
I had to wiggle a wire into the area by the frame pin and pull the hook to disengage. It was a major PITA filled with a lot of explicatives. Once free I fixed the linkage and even hooked up an emergency pull so it would not happen again