I find the Forrester, Maze, and Drill Seargent to be more geared towards teleporting and repetitive non-area skills (I.E. NOT Fishing, Woodcutting, where you have trolls, ents, ect.).. Alching (I've done A LOT of Alching.. I know..) hasn't actually got me as many randoms as Alching, then teleporting, or teleporting in general.. After even running somewhere, then teleporting, I seemed to get him a lot. You can't force him on you though, so don't sweat it.. You'll get the set eventually. :)