There's a lot of disassembly to get to the chuff switch on many of these, and the CC2 is no exception! 
Be careful taking the shell of that one, it's pretty busy inside! The newer Vision Line locomotives have a much cleaner interior and are a lot easier to work on.
You have to drop the front truck to extract the switch. That involves removing the shell and usually moving stuff out of the way to get to all the wiring and screws. 
Usually, a simple forming of the contact lever returns it to normal operation, occasionally you need a new switch. You can check the operation with a meter while you have the truck off before you stick it back on. The ones like the CC2 with the 4 lobe cam are trickier to get adjusted properly as the switch travel isn't as great as the two lobe cam models from the TMCC era.
