Thanks, I managed to find the software but only version 1.0 from versiontracker.com, it certainly worked in terms of finding hidden files but unfortunately not the missing songs files!
It is curious given the files are actually on BM5 and playable but simply not visible from my MAC. One option of course is to delete all from BM5 and copy again, although I'm reluctant to that unless nothing else works.
Gavin