Both mechanical travel stops are part of the camera shell, and are hidden by the left axle hub cover. The "UP" stop is part of the REAR shell, near the top left screw. It normally stops on the top edge of the left arm, but may have bumped past it and is now hung in/on the forward facing part of the left arm. You will not be able to see it with it jammed in this position. You may be able to get something in the area to push things around enough to get it free. It may be possible to remove either the nose piece or the front shell, and get some access (probably not, with camera jammed up). Otherwise, you will have to remove either the rear camera cover or the left arm cover.
Not related to your issue, but the "DOWN" stop is located on the left side of the FRONT cover, just below the lens. Remove the four outermost screws on the rear of the camera, wiggle and pull the front cover out and at an angle (out more on the right side) until you can clear the stop and put the camera back in the right position.
For either stop, if you remove the left arm cover to gain access to the stops, you may mess up the label unless you are very careful.
If the travel stop is not your problem, please send a picture of how the camera is positioned.
