I'm not a fan of creating a macro involved in the drudgery of testing every word so I'm thinking of 'out of the box' solutions to see if there is a clever solution to this problem.
One option I've thought of is to make use of the spell checker with the option to
Ignore words that contain numbers turned off. This will give you a red fuzzy underline on all of the codes you appear to be searching for. Plus, we don't even need a macro to review all of these because you can just use the Spell Check to progress through them.
A macro to harvest these 'spelling mistakes' into another file should be easy enough and run faster than examining every word in the doc. You might want to exclude misspelled words that don't contain a number but that is not too difficult.
I've also considered tagging the hits as either a TOC entry or and Index entry so you have an in-document way of listing and navigating to the instances.