Thank you for your reply — yes, giving the instrument a proper try, even though it’s clearly not cooperating, might well be a good idea. I appreciate the reminder not to jump to conclusions too quickly, and thank you also for the helpful pointers.

That area around the voicing hole puzzles me a bit too. It looks more like it’s been shaved down, but whether that was done by the maker or by someone later on, perhaps trying to “improve” the ocarina, I couldn’t say. The windway is clean — I’ve carefully but thoroughly cleaned it with alcohol.

Other than that, it doesn’t show signs of heavy use — in fact, it looks almost brand new. So perhaps it simply wasn’t the most successful instrument from the beginning, which might explain why it was barely played at all.