Coupe door won't lock and springs back up!

I was having issues with my 95 328i coupes passenger side door lock acting weirdly since the beginning of this year, first of all the central locking wont engage it properly and I would have to be manually push the tab down from inside the car, but now all of a sudden since this week, the lock even when pushed down manually wont stay there and instead spring right back up. I think its a mechanical error and not electronic.

any body got a schematics or common resolve to this issue? not really safe to park it anywhere now :(

Coupe door won't lock and springs back up!