I just found out that my scanner was playing up. The scanning light had fallen off the tracker beneath the glass.
Rather than bin the thing I just thought I'd have a look at repairing it. This si how I did it:
1. IMPORTANT- disconnect the mains supply and USB lead.
2. Remove the scanner lid.
3. Lift the printer cover as if you were changing the ink. On the right you will find the red support catch. At the top of this catch, pinch inwards at the sides to remove its hinge from the printer lid. At the joint of the printer cover and the base there are two grey hinges. Take the left hinge and move it sideways slightly. This will free the lcover enough to access the screw holes.
4. Remove the 4 screws then close the whole cover back down. slide a knife below the control panel and pop out the catches around the edge of the scanner top. this can now be removed completely. Be careful not to break any catches.
5 You now have access to the scanning parts of the machine below the glass to carry out any repairs necessary.
6 When you have carried out your repair, simply reverse the process for dismantling.
It worked for me.
I hope that this may be of use to anyone else.