[mole42uk]

You need to have the printer powered on, lift the lid and then press the blue "change pen" button. This will bring the carriage into the change position and you can use the tab to lift the top pen. Once you've changed that, the "change pen" button selects the next pen and you repeat.

There's a place in Germany where you can buy new pens. If you need it, I'll find the address for you.