maybe try here:
BLAUPUNKT Cheyenne CM42 Service Manual on eBid United States
good feedback...
Feedback for: vintagedeptstores
from what i've gleaned on the internet, trying to remedy a missing code is pretty difficult. think i'll put mine in a safe place before i lose it. good luck
edit...might contact the fella that sold you the radio. maybe he remembers the code, or kept a spare copy somewhere safe, like with the car's registration papers.