Lift up the inner casing of the bottom half to access electrical connections to the element. Pull away insulation covers and undo screws eg orange arrow.

To make access easier, you can also remove the earth connectors and the thermal fuse (purple arrow) from the inner casing. If you have a multimeter you can confirm that the thermal fuse and thermostat (blue arrow) are closed circuit ie near 0 ohms.

The lower heating element can now be extracted.