On the style 300D that you have, only being able to operate the driver doorlock plunger when the door is closed is normal. It helps keep owners from locking the car while the keys are still in the car. Your other issues are likely being caused by sticky or dirty tumblers or leaves in the lock cylinder. There have been a fair number of discussions about this issue in the recent past. Just use the search feature and you should find at least one.

The good news is that cleaning with the appropriate materials is usually the answer, and new locks or keys are likely a way down the road !!

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1961 190Db retired
1968 220D/8 325,000
1983 300D 164,150