Got it!, I 'm familiar with the W116, W123 and W126 consoles...I hadn't seen that style before.
The photo really helped!

From the photo it looks like you need to wedge a small screwdriver or plastic bone tool between the side of the plug-in connector and the outer "ear" on the plug holder.
This should allow you to free the plug-in connector from the plug holder.

As to why the the PS window function failed...possibly frayed wiring near flexure point in PS door, bent regulator, siezed window motor, loose/corroded pin receptacle (female side) of console PS window switch connector.

I'm leaning toward the last option, as you had intermittent operation of the PS window when you pressed harder on the PS switch.
You should be able to open the plastic body of the plug-in connector and remove the wires (take a photo of wire locations beforehand to aid in reassembly).
Lightly, gently crimp each female connector so it will have better contact with the male pin when the connection is renewed.

Hope this solves your loss of PS window function.

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022