I did a quick internet search as most instructions are online nowadays, but didn't find a link, and I expect you've done the same anyway. If nobody on here has access to the instructions, you could contact The Incubator Shop https://www.theincubatorshop.co.uk/prod ... ators.html They do spares but don't list instructions. Helpful firm, though. Maybe they might be able to send instructions online.
i suppose the person who gave you the inci has lost the instructions? Can they remember how it works?
https://www.ebay.co.uk/itm/Corti-25-Inc ... Sw2Zldzqjb