For those of you who don't know, Zimbo is a special custom-made vendor that has some rather cool stuff, including potions that allow you to "transfer" unused AAs from one character to another although at a price. You can find him in the Hidden Forest wiki...www.hiddenforest.org-->click on wiki-->scroll down the column on the left till you see the one labeled "custom extras" and click custom vendors.
Note that this post is for finding the Zimbo in the normal server, not the Zimbo that's on the test server (does the test server even exist anymore?).
Zimbo is located in the middle of the Qeynos Aqueducts zone which, in the lore of Norrath, lies beneath the city of Qeynos (its actually just another zone). This zone is a literal maze, with several elevations and water-filled tunnels. It has some lower level mobs which don't agro if you are 70 (except for skels).
Being how its a maze, and that our map does not do well when trying to figure out crisscrossing tunnels that are at multiple levels, it can be quite a chore finding him. So here is a shortcut that I found is easy enough to memorize (after making a couple practice runs).
1) Zone into North Qeynos using Elyse, the Normal Zones Teleporter (no, NOT into Qeynos Aqueducts). I guess you could use a wizard instead...
2) You land in the zone facing one of the entrances into Qeynos. Look a bit to your left and you'll see a wall tower. Run towards it, to the left so that you pass it and you'll see a part of the wall that has a vine on it. That marks a fake wall. Run thru it and you will see a well (you can see this well on your map). Jump into the well. Swim down the well until you zone to Qeynos Catacombs.
3) In Qeynos Catacombs, swim down till you hit the bottom then turn around and you'll see a short passage. Swim down the passage and them swim up and out of the water. Now you'll see another passage in front of you. Run down it till you hit a wall.
4) Turn left and continue and you'll end up in a small room. In this room, you can either go left or right. Go left...you'll see a bloodstain on the floor. Follow this past the green stain on the floor until you reach the room that has a big square pool.
5) Run towards the left, across a corner of the pool. While still looking to your left, you'll see an oval golden sign that says Qeynos Aqueduct System. Its a fake wall so run thru it.
6) Follow that passage to the left and downwards. Run until you hit a four-way intersection...to the left is a drop to another part of the zone, to the right is a passageway that eventually leads to Zimbo, but forward is a drop that places you right behind Zimbo. So...yeah.
I had to find Zimbo rather early during my return to Hidden Forest. I found that some AA Abilities needed to be repurchased and that a few new ones (or at least new levels of old AA Abilities) had been added. I assume it was due to the change from a Titanium-based server to an rof2-based server. This would normally have required a huge grind fest for me since each of my six normal group members needed an average of 400 AA points, but my two main toons had like 10k each of unspent points.
Added note: after you purchase an AA potion, give it to the character you need the AA points on. Then have that character hand the potion back to Zimbo. Be careful to NOT hand the potion to your pet. I don't know if you can hand in stacked potions...I didn't try...but you CAN hand in one potion per item box in the trade window.
Have fun.