I have three vintage 25J Sekonda watches with a day/date calendar window and for some reason, the calendar function is faulty in all of them. I notice that these watches, all versions of the same model including an identical example, feature an odd mechanism on the side of the case and I am wondering if this mechanisms has something to do with setting the calendar, or is the calendar on my watches just broken. I show this model here below, including the unusual (push and slide?) mechanism, and would be most grateful if someone could explain this feature/mechanism to me (pics below from agnieszka0302 on eBay):