6 volt coil cap removal? How is it done?

[kookie1]

Can someone tell me how the get the cap off my 6 volt coil, 1937 Pontiac 6 Touring Sedan?   I've never seen the inside of the cap so I don't know how to release the catch.   The shop manual says use a special tool J-729, I think that's the number, but no picture of it is available.    I used the approximate position on the coil shown in the picture in the manual and tried to push a .008" feeler gauge up alongside the cap.   Needless to say that doesn't work.   When I twist the coil I can feel the catch stopping the coil's rotation.    So, can anyone suggest what they've used instead of this special tool to get the cap off the coil?    Thanks!!

Edited July 21, 2016 by kookie1 (see edit history)

[kookie1]

Well, I took the whole thing out of the car, coil, cable and lock.    It's sitting on the work bench and I still have no idea how to get the coil off it's cap.   Chewed up my hand trying to use a feeler gauge and I've finally given up with the feeler gauge idea.    It's obviously not going to work.   I can't believe no one has a picture of the inside of the cap and coil laying around.    Surely I'm not the first person with this problem.    Does anyone have a picture of the inside of the coil cap?     I'd settle for a picture or a drawing or even a drawing of the special tool.     Any suggestions would be greatly appreciated too!!

Edited August 10, 2016 by kookie1 (see edit history)