On the top panel, at the back , there are 2 catches, one at each side. Using a screwdriver, prise each catch while slightly sliding the top panel backwards. Once both catches are free, slide the top panel backward and lift off.
Once the top panel is removed, there are 2 screws at the front of each side panel. Remove the screws. At the back of the side panels at the top, each one is hooked over a small nipple. For each panel, spring the panel off the nipple, then gently spring the top of the panel outwards & lift away.
The front door panels is removed by removing the screws round the edge, then lifting off. Replacing is a little tricky - there are two plastic spacers that may fall off when you remove the panel -these slide into slots on the hinges - put them back before replacing the panel.
Andy Joiner, January 2008