Originally posted by stevebrot Note the orientation of the adapter. I may be way wrong, but based on the position of the backside cut-out (where the spring installs), it is about 180 degrees off. Camera bottom is to the right in the second photo. Note that the OP stated that the spring is already removed.
Steve
The adapter is no longer listed on Fotodiox's site but there may be new old stock out there for sale.
There is a reason for the red dot on the adapter.
The OEM adapter can be put in 180° off. The spring normally prevents this but if it is removed or you press the spring in the adapter can be inserted.
Simple: just line up the notch to the red dot as pictured below, hook a finger nail in the other cut-out, pinch and lift it out starting at the side you are holding. Do not lift straight out. Tilt it out.