G'day Rod, What firmware did you use to recover?
I don't understand what you mean by "need a dump.bin to suit "
The CTW500 is a Glacier isn't it?
If it is, there is a firmware file on the UXcell website here >
http://www.uxcell.com/public/mp3upda...ine_061031.rar
EDIT: It could also be the Osmium here >
http://www.uxcell.com/public/mp3upda...INE-061218.rar
Maybe they'll work