OFF THE BANSIDHE'S MAP - Help

My Thief was TPd by a chest trap to an area seemingly beyond the Bansidhe Lair map. Doing a locate spell by my seeker says I am 11 spaces to the right of the right hand most vertical column. That would place me 4 spaces to the right of the extreme right border line on the current map (column 23). I know the X,Y coords are estimates, but using the current map as a start, those numbers would place me at what would be 34,15 on the current map.

Using my thief location and the seeker locate spells, I have determined where the correct West border of the Lair is and left a separate message to update the Lair map.

More importantly, displacement and teleport spells do not seem to work in the Lair. So I am unable to displace to the stranded thief. The thief is not strong enough to move about alone on this level.

I have not yet found any space where displacement or TP spells will work so am now assuming it never works here. All of the area outlining the mapped area is rock so there is no option to etheral spell to the thief either. I have visited all the mapped rooms and not discovered a secret door or a room linked to the thief's location.

I have run out of ideas. Anyone have a hint how to rescue my TPd thief from the void under the existing conditions?  Please.

I will come in with wolf if anyone is available to find a solution (or at  least a hint).

Mike