My 40th is the third C4 I have owned, and I have had the door panels off on the others many times. If your panels are flopping on the upper edge, then they're already half-way off. Unscrew the 6-8 screws around the lower inner edge of the panel, then start looking for the others behind the inner door handle, and behind the rear edge, by the hatch release button. Maybe one or two at the armrest handle. The early C4s were tougher because you'd have to take out the speaker in the door. Now, carefully lift the panel, making sure not to rip the wires. They all can now be unplugged. Pull back the plastic moisture shield, and the lock actuator is in the rear of the door. Cycle it a few times, so you can see how it works, and lube the pivot points. A few more cycles and the tired part will act much younger. Put it all back together and less than an hour will be spent on what you did. Buffing and cleaning the contact points on all of the connectors can also be time well spent. Dielectic grease will keep those contacts efficient.
