Rick,

I just learned about these lock actuators last week, I think I can help. My car is a 1982 300SD.

Assuming your actuator is a OEM Mercedes actuator and not a VDO. OEM are all dark in color and the VDO's are blue.

What you need to do is hold the insert "with the Wedges" as you gently tap the part around it, the looks like a Knob, while the Knob is extended, UP; which is UNLOCKED.

The best way to TAP around the "INSERT w/Wedges" is to use a pair of pliars and use the HOLE part of the pliars to go around the screw, see below.

The best way to hold the insert is to get a long straight threaded screw that fits EASILY into the hole and push it sideways into the grooves of the insert, then TAP it with the pliars using the hole in pliars to go around the screw.

MAKE SURE ACTUAOTOR IS EXTENDED. Gently tap it.

The insert will slowly show itself and will come out about 5/8" and then you can put the rod in from the side.

Let me know if this helps.

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1982 300SD