That is why I left that outside spring off...binding. The brake cam slides in and out just enough that the spring can not be replaced without having the wheel apart. Then you can push it out from the inside and position the spring.
Stupid design.
guess they wanted it tight to protect the O-ring...but water can enter from around the drum anyway. Probably required by a lawsuit from somebody who never lubed anything.
In any case I'm happy with the Dyna mount, no leaks, no binds.