in reply to Perl archeology: Need help in refactoring of old Perl code that does not use strict

Further to Corion's wise general advice, I would add to

... find and collect the global variables ... and then [remove them and] pass the parameters explicitly instead of implicitly ...
that if you can also identify a global variable as, in fact, not varying during program execution, you can convert this variable into a true constant and thus remove a potential headache: a global constant is, in general, a Good Thing (or at least no Bad Thing).

Give a man a fish:  <%-{-{-{-<