Trouble finding NPCs

[Ur Dragon]

Since the Adveturer's update, the game shows how many NPC there are in each map and I noticed I haven't met some.
But going to the islands I still can't find them - one in autumn springs,(found the hunter, the collector and the merchant) one in Witchwater (found the geologist) and on in the Great Frontier (found the knight and the merchant)
I looked around the entire islands, even used blocks to look under them for caves and in the floating blocks and still havent a clue on where they are.
Does anyone know about a way to find NPCs faster ?
Or a clue on how to find those I haven't found?
(regenarating the world makes every NPC on all islands to go back to not met, so I'm trying to avoid doing it)

[Sangria Dracul]

i just found Azak the Hermit in Witchwater underground. Only reason I found him was because I jumped into this hole to grab a chest and as I was killing a mummy I heard his voice on the otehr side of a dirt wall. Grabbed my drill and there he was in this small hut (I'd post a screenshot here but I don't know how)
The one in Autumn Springs is also underground somewhere... I found him behind a dirt wall inside a dungeon on my world
Honestly I wouldn't go through the trouble since they're useless... No quests/items and you can't take them with you either...

[felixader]

Just pushing this up top so people having the problem find this.

And I want to add that some of the NPCs **that are important for quests** have the same issue.

Thanks for the hints, even 8 years later.