These heaters aren't made to be serviceable. But I managed. On one side of the heater is a metal cover with all the controls on it. If you turn the heater upside down you will find the metal cover is held in place with a metal flap bent over the edge of the heater. If you bend this up with a screwdriver you can ease the metal cover away from the heater. Ensure the heater is switched off when you do this.
If you do this, you should be able to get a screwdriver in to undo the screws on the plastic cover. All the screws are pointed towards the outside of the heater. There are four screws holding the plastic cover in position. Remove these.
Then there is another plastic bit which holds the centre bit which the mains cable wraps around. This is held in with four screws. If you remove these four screws you can then remove the plastic cover where the mains lead goes in and underneath is a mains connector block. From here you should be able to replace the mains cable.
I never found out how to remove this whole assembly at the top but I managed to pull the metal cover away from the radiator enough to be able to replace the cable.
Ed, December 2011
