Hm whole new world to me Roll Pins, they could be but do not appear to have the slot to my eye. Complete new set of tools required for removal and putting back in. If they are I would suspect that Piko have special tools to get into the small places where they are fitted into the gear. Interesting suggestion though.Are they mini versions of what I believe are called roll pins? I had to dismantle my mum’s Stannah stair lift some years ago and the ”track” was held together with these pins which, once I realised what they were (!) simply tapped out. The pins typically have a chamfered end so inserting them is relatively easy using either a press of some kind or an appropriate punch.