If you do not want to replace the camera, take a Clorox wipe or iFixit Screen saver and apply it to the part of the glass where the camera sits. By that I mean to clean the lens of the camera. Dirt, fingerprints, and hand cream in the case of my parents might be on the lens blocking it. IF that does not work then go ahead and swap the cameras. Since they are different cameras they may not fit and their cables may be different but try and if you issue does not clear up comment back here.