Well I was wrong on the wire, it actually has three conducters inside for the locks and the alarm. There's a big plug on the end of the door, remove that and the connection plug for the wire can be disconnected, so now the whole lock / tumbler assembly comes out.
This site discusses 201 door lock repair:
https://www.coolcatcorp.com/Mercedes%20Locks/Door%20Lock/190%20Door%20Locks.html
His procedure is very close for a 124. My lock required only the tang pin to be removed, the other two pins are in blind holes. Once that pin was out, tang assembly comes off, and then the tumbler can come out with the key inserted and turned 90 degrees to either the right or the left.
Careful! Don't pull out the tumbler too fast, easy does it, now you have access to all the wafers and springs, and there is a little ball bearing that lives in there too, so don't loose that.