I haven't used the '85 325e for a month and now the door latch on the driver's side won't stick upon closing and thus the door stays open. Can this be removed and cleaned easily by removing the 3 screws? Any fix suggestions appreciated.

I don't know anything about E30s, but if there is any similarity to E36s then if you remove the door panel there should be an access hole on the inside of the door to remove the lock from, after you remove the screws that hold it onto the door. Are you sure it's something that would be fixed by cleaning? Maybe it's just "worn out" and needs to be replaced. Maybe if you remove it you can play with it and see exactly what is wrong once it's out of the car.