I only can recall those:
- Heckel funch (the gnome in the first level of the stronghold)
- Martin Thwait
- Dig in the middle of Mort'ton
- Doomsayer
- ?
- Lumbridge guide
Sorry, I really can't recall what the 5th completable step was... I already finished 6 or 7 clues after writing this post.
I have a feeling that it only appears on the first clue box. Maybe even hard clue only since I did exclusively hard clues.
I have unlocked Kandarin, Asgarnia and Morytania.
Possible clue steps on Karamja:
- Red spiders egg spawn
- Saradomin mage right on the volcano entry on crandor
Possible clue steps in Asgarnia:
Misthalin:
I think those are all I could have had. Just in case those weren't it: I had no step in kandarin except heckel. I had no step in asgarnia except martin thwait. I had the doomsayer and the lumbridge guide a bunch of times. I only had the mort'ton step in morytania.
If it helps, I can provide my ign via pm so you can do some digging there.