Key Broke off in ignition 94 Cougar XR7

Can someone please help. I have a 1994 Mercury Cougar XR7 and the key broke off in ingnition. Problem started when outer part of key switch would turn 360 degrees. Key would not line up properly, at times. I would have to manually turn outer piece of switch, to line up. Now the key broke off and part of key is still in the switch. It will start with a small screwdriver, but would like to fix it....Do I need to replace ingntion tumbler and if so, is this an easy task with the airbag..I have replace tumblers in Chevy's before, so I would like to tackle this job myself...Thanks