Okay so already defeated Vokun earlier. Recieved Shalidor Insight quest at High Gate Ruins. I went through everything. But when you get to Vokuns throne room he does not respawn, nothing there to kill. The gates to the treasure chamber will not open. Totally screwed.

But then I returned to the first chamber of Hight= gate ruins. Up above on left is the ledge where you exit the throne room treasure chamber. Using a combination of jumping up the leaning pillar in the left hand corner and then shouting mid jump (whirwindsprint) I made onto the ledge. only took me two minutes of trying so not impossible. Now for the luck part. I found there is another gate there closed. I stood there ready to scream. Suddenly my NPC appears on the other side of the gate. Oh ya. I ask here to pull on the chain. Gate opens. Quest completed. Note that you cannot open the chain by yourself. For some reason with the NPC the reach of your effective commands is extended so there it is.

Good luck!