Thanks sean. I can see exactly what you said and moved the white bit to one side - but could not slide it back again to engage the handle. In my struggles, the whole mechanism slider came off and I cannot see how to put it back again. The cable needs to be threaded and there are 2 locator pins in a space that I can only get one hand in and then only just.
Do I need to take the lock mechanism out and try to fit the handle again afterwards?
Charlie
June 2008