Failure in Mercedes C-180 gasoline in 1995

Hello, I am new in the forum, I would need the Spanish workshop manual of the Mercedes C-180 gasoline of the year 1995. Well, I have a breakdown in the centralized closure of the doors. The left back door does not end up closing me, sometimes with the command, and I have to finish doing it, manually. If anyone knows how this closure works, I think it is pneumatic, but I don't know anything about the schemes, and before starting to disassemble, I would like to know a little more.

Thanks and greetings.