This is what one person who camped the courier said:
here is the list of mobs with exact spelling that i found on the cycle:
a sabretooth cat
a sabretooth tigress (rarely, and lots of tigresses around that are not on the cycle)
a goblin brawler
a goblin skirmisher
greater scalebone
greater skeleton
an Iksar marauder
an Iksar brigand
a Sarnak youth
a Sarnak flukie
a Sarnak courier
hope it helps
you need to keep killing the newest (up on the list with "normal" sorting) spawns that match these and you will get a courier every 15 mins or so.
after 7 hours of camping (and about 30 or 40 courier kills) i finally got my Goblin Gazughi Ring)
He also dropped this ring earlier:
http://everquest.allakhazam.com/db/item.html?item=1654
hint: stay between the ruins and the windmill, if a cat or marauder appears on track and is not in the near vicinity, it is not from your cycle.
on another note: after a while, i noticed a 2nd goblin skirmisher on track, and killed both, after that i had 2 cycles running (for much quicker killing), looks like there is more than 1 slot on that cycle there.
This now is me...As Glitch said, I have yet to see a goblin skirmisher or brawler in this area he describes. I also have not seen any sarnak except one sarnak conscript, and it always spawns as a conscript. No youth, or flunkie. I also have not seen an iksar brigand here, only marauders roaming through. There are also a few spawns that seem static not far from windmill toward those ruins, they should all be roaming. I Have seen plenty of skels, but no greater skeletons here. Then courier should be fairly common, they post about getting up to 40 kills of a sarnak courier, in 7 hours. The reply to this post the fellow mentions getting 2-3 couriers every 15 minutes killing these mobs.