The post (on the chassis) and the conical receiver (on the door) had gummed up. A dremel cleaned them to shiny condition.

The latch inside the car worked fine, but it took a strong shove to open the door from the inside. Also check alignment of these 2 parts, when closing the door

__________________
1970 280S M130 engine- good runner
1971 250 M130 engine- #2 rod bearing, gone
1971 280SE (blown engine,parts car)
1977 German 280S W116-only 33 years old