I've been searching for a Presslok for my Super Graphic for nearly 25 years. Good news, I found one NOS in a box, cheap. Bad news, even though it's in mint condition, springs are strong, etc. it will not lock to the base of my camera. It appears that the keyhole-shaped slots in my camera have the shoulder too deep so that the heads on the Presslok studs won't lock into the taper.

Was there a mid-model change in the dimensions or specifications? My SG is circa 1959 and the Presslok is a model 4595. I could possible take a couple .001" off the underside of the heads on the Presslok studs and make it work.

Any thoughts?

I had 4 Super Speeds and one presslok catalog number 4595. ( Take a look at the last page of the Graflex Graphic Camera Brochure on Camera Eccentric, there are different catalog numbers for the Super Graphic equipped with different lens and accessories, 7 catalog numbers for 1 basic camera. http://www.cameraeccentric.com/html/info/graflex_7.html ).
The presslok fit tightly on 3 of the bodies and would pop off the 4th. I examined the body and discovered that the slots were slightly thicker on this body than the other bodies. I did not measure it with a caliper.
The Super/Super Speed service manual only lists one major body change, serial numbers higher than 646124. The service instructions clearly state that the differences between pre and post 646124 cameras is in the parts installed. All 4 of the bodies were post 646124.
I assume there was a production error or an occasional miscasting that caused the presslok slots the be improperly formed on some bodies. I believe the error to be the slot, which rise at a steeper slope by 1 to 2 degrees.
I have 1 Super Speed and mint presslok that fits it securely and I will attempt to measure the slots if necessary.