It will be the same as with the Philips HD 4600A.
First you'll need to remove the back cover (one screw). Remove the 2 neon lights and the tight strip holding the wires. After that you need a small scewdriver to pull the black holder down a bit and over the edge. (For the HD 4600 it is necessary to remove the outlet plug connector, otherwise no way to remove the switch). Replacement switch & Filter can be obtained at spare2go. Make note: in order to remove the inside parts, you'll need to remove the handle as well! You'll need a hex tool for that in the inside of the kettle This is a bit tricky, screws are tightened with blue glue as well . Now still 2 screws are helding up the side holder. There is a rubber seal inside. Depending on the condition the seal, it might still be possible to 'rought up' with fine sanding paper.
My kettle suffered from a faulty switch though, so it didn't switch off in time, this caused water leaking through the switch cover.
Before ordering it is wise to judge the overal condition of the kettle before ordering parts. Most of the time you'll need to replace the on/off switch & filter as well.
robert, November 2006