Damn, I wish someone answered this. I am about to replace mine. Same problem with the Super 90, I called SIME Ltd.
Unit D2 Enterprise Way, Bradford Road
Bradford, West Yorkshire, BD10 8EW
Phone : 08709911114
You can get a new timer clock from them for about £50, but they also gave me a number for a local plumbing supplier in London, so picking that up for £40. Not sure If i should attempt changing it, but will have a look see what needs to be done
Iain, November 2007