Fixing old Penguin Gemini Lighter for a friend

Hullo peeps, so my friend and I recently went antique shopping and found a neat little Penguin Gemini Gas Lighter that she bought and wanted me to fix. The gas part works all fine and well, but the flint wheel seems to be a bit stuck. It will turn when you press on the button but then it goes back down, not doing the whole spin and not really sparking the flint either. Apparently, it also won't open for me to have a good look, as it has no screws and only a little pin I can't seem to pull out. I've tried to lubricate it with WD40 but still no luck. Any ideas?