Here's some photos of the inside of the rear drum;
DropBox Link I'll take a guess that the cable has come adrift from the actuating lever inside the drum. Not really anything you can do about it without taking the wheel out which is a bit of a adventure the first time you do it and remains a bit of a slog each time after that.
Here's another Dropbox link;
Rear Wheel Removal and Fitting Hopefully these links just work, if not I'll sort something out!
