Turn the heater control to 2 (or 3?!?, so its at 12 o'clock IIRC) and wrap it in masking tape (to prevent scratching) then the dial knob pulls out (be uber careful). With long nose pliers you can reach the [tiny] bulb inside. Theres only one bulb.
The bulb is quite tough, but if it breaks you'll have a fiddly a job getting it out.