I have not read of anyone with this issue but I looked for threads concerning the lock. Maybe there is some pictures that would help give you some ideas.

From our sponsors blog???
https://www.pelicanparts.com/techarticles/Mercedes-W123/82-BODY-Rear_Lock_and_Latch_Replacement/82-BODY-Rear_Lock_and_Latch_Replacement.htm

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