The MEl/CDL/DDG does not cover everything, just because its not in there does not mean you can not fly.
Here's one, B744 - brake unit has 2 wear indicators, on your walkaround you find 1 missing, it's not in the MEL/CDL/DDG, can you depart without having to lock out or replace the brake, after all it's not in the DDG?
AFAIK, if the DDG gives no relief, you cannot fly without a special Engineering Order approved by the FAA (N-reg).