<p>We've got dozens of versions of an SWF modified for different customers of a big Flash project, and now would have to replace some strings embedded in scripts in each copy. The FLA file for some of these is very difficult to locate or even missing (I inherited this mess and refactoring it is currently not an option).</p>

<p>Is there a (free) tool to replace strings used inside ActionScript? I tried swfmill to convert the files to XML and back but it can't handle international characters contained in the strings so I could get them only partially converted. Most of the strings were correctly extracted so another tool might do the job.</p>

tricky - it might not be any easier, but you could load the 'locked' swf into one you control, then spider through its objects until you hit TextBox, using some for...in loops - it'd be a long, arduous process to map them out then change them, especially if the previous developer didn't name things in a helpful way, but if it's a fairly simple .swf then it might be too bad...
Also, there's a mac-only utility for decompiling swfs that I remember a coworker swearing by, but I don't recall the name... anybody?