I am in the exact same boat as you were in. Key broke off inside, switch not in off (0) position etc. However my tumbler assembly has a slot/hole for only 1 wire not 2. How did you cut the black housing away? Dremel? Rotozip? What did you replace the black housing with? Were you able to unscrew the black housing? Which direction did you turn it CW or CCW? I also have a replacement tumbler and key but I am stuck.