The thumping noise is normal. If you have ears good enough to hear it.
Please understand I have only worked with four of these cameras. But of those 4, three had the issue I am about to describe. Two are now in the junk box because the repair parts are not available to the public.
The thought is that the main camera ribbon may have come loose, and is catching on a particular screw, or on the edge of a plastic plate. Both are located near the final run of the ribbon. The problem seems to occur if the camera ball gets rotated in either direction with enough force to jump past the normal travel stops.
A quick check for the condition MAY be possible by placing your ear very near the left hub, and carefully listening for a slight rubbing or clicking sound as you move the camera up and down by hand. "Left" meaning as viewed from behind the drone/camera.
Actually checking for this condition requires removal of the left arm cover.
Important. Try not to move the camera excessively in relation to the arm. The ribbon is very easy to break, and it can not currently be replaced. The camera is totally useless if you break the ribbon. It may be a better option to send it for repair.
If you choose to attempt the repair, put the gimbal lock in place (if possible) and leave it in place while you are removing the side cover.
1.) Remove the black disk from the arm cover. You're going to do some damage to it. It is held on by very strong glue, and almost no clearance to get under the edge. Be as careful as you can, and maybe only limit the damage to a couple of small nicks. A new set of covers cost about 20$ if you want to return it to new looking condition. If you can find any.
2.) There are two screws under the black disk. Remove them.
3.) Next is a bit of a question. Some cameras, the arm cover just lifts off clean and easy. Other cameras, some black glue got slopped between the main ribbon and the cover. These can be a real pain, and put the ribbon at great risk trying to get them separated. Tilt the cover a little, and carefully try to get the glue off. If you break the ribbon, the camera is pretty much finished.
Once the cover is off, you will see the ribbon run down the side of the brass bearing housing. Follow it down about a half inch, you will see the ribbon make a 90 degree elbow. The area around the elbow is where things hang up. There is a plastic plate below it that gets caught if the ribbon is glued too low on the bearing housing. There is also a screw that gets caught if the ribbon is not glued in tight enough around the edge of the bearing housing. You just have to look, and move the camera ball carefully back and forth until you see if and where the ribbon is hanging. If the ribbon is hanging or rubbing on anything, adjust the position of the ribbon, and glue it in place.
Again, I am not the most familiar in the world with the C23. Maybe someone else can offer something less risky as a remedy.
