The coupling is supposed to be about 30 degree to the right and not left of center so it's not in the right position. It's spring loaded to return to the right. You can push it back and forth. Won't do any harm. It could be a bit sticky. The fact that it's slight left of center then the camera think the lens is stopped down a few stop and thus your wrong reading. In another word, give it more exercise.
Originally Posted by starcade design