I'm having trouble removing my light switch at the back of dash -- got the switch itself off. Following the manual instructions it says 'remove the ferrule retaining nut with the appropriate tool' but where exactly is the ferrule nut? and what is the appropriate tool? The nut has to be holding everything in place but it's hard to see back there and I dont want to force anything and end up breaking something. Everything is old and hard to get loose. Anyone know how it comes apart? Thanks.