Electrical connector at rear of ignition electrical switch w123

[Zacharias]

I have the entire ignition lock assembly dangling out under the dash of an '84 300td parts car. I need to swap over the lock to my '85 300d and install at the same time a new electrical switch and tumbler. (I removed what I thought was a sticking tumbler to find that the problem is with the lock mechanism.)

Here is the issue: I cannot get the plug out from the back of the electrical switch. I have tried prying it, and pulling/jiggling/twisting it by hand and with a set of slip-jaw pliers. It does not want to come out.

It isn't my parts car, so I don't want to cut the harness.

Anything I am missing on this? I have my new electrical switch in hand and I don't see anything that would be holding the plug in there, except age(?).