Ray, if you google "taping the pins on the canon 100-400", a site will come up that shows exactly how to do it. You tape the pins on the converter. If you do not share the converter, with say a 70-200, you can leave them taped permanently. I've used a small piece of scotch tape and it never falls of, no matter how many times I take the converter on and off. It's very easy to do in minutes, but you loose some of the reporting data, which is just for your own history of the shots. Let me know if you need more. It works very well.
What I want To know, is if it works with a 2x!, because I want to get one.
Good luck. ;-)
SS