I have found a crude fix. The main problem is more the camera case corner than the back plate. take off the camera back plate ( the camera PCB is held in place by the back carefull it is loose also dont let any dust in) file all four corners as in pic_1 & Pic_2
then re fit the filed plate then take off the case corners until it misses the yaw arm one file at a time until you get it right. Pic_4 is how I tested it works before modifying the back plate
Cant see any other way to fix the issue as the camera case corner needs to be filed as well as the back plate corner
Note: the camera case is not square 32mm x 30mm see Pic-3
wash the back plate after filing before refitting so as to remove any dust