I could swear that there was a final answer but here is one thread: http://www.peachparts.com/shopforum/showthread.php?threadid=17563&highlight=central+locking+power

You might use this thread to continue the search. There may be a separate "fix" post.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician