How do I fix my Tefal Pro Express Rewind?

The rewind is not working properly, in that it seems the cord is stuck mid length. I can get it to take the rest into the base, but can't get it to release past half way. This means that I can't reach the plug from the ironing board!
The bottom seems to be sealed with strange looking screws, anyone got any clues please? Other than this, I love this iron and would buy same again (if I won the lottery!)