What's the trick to removing 1970 Dart wiper switch?

There's a little button you have to push to release the knob and shaft. To reinstall, it just pushes back in & snaps in place. Then you have a lot more room to get at the collar.

http://www.carparts.com/details/Ply...gclid=CIzgtKLP2NMCFYI7gQodgRIELw&gclsrc=aw.ds