To find this guy, do NOT go inside the instance. When you get into the train station area don't go towards the instance (left), go the other way (right) towards the back door.

There is a large circular platform ahead of you; Namdo is hiding under the back (northern) side of it.

This guy ONLY sells to Alliance ... if you are Horde, and hate alliance, then kick his butt.

There's a mailbox in Gnomeregan (Gnome-re-gon) as well. I don't know if Horde can use it, my hordie is only 20, but I've ran it quite a few times.

first of all, this dosnt get sold by a shopkeeper, its givin a special machine u have to have a key to access, ive got it,its not that hard, im pretty sure its in gnomeragon part1 not the workshop, but the key drops from the leaper gnomes found outside the workshop, all u have to do is kill sum, hope it drops, then go to the lesser machines to get more schematics and better keys. and if this helps,the drop rate is about 2/11

Schematic: Minor Recombobulator

Is sold by Namdo Bizzfizzle in Gnomeregan, and he is NOT in the instance, just a normal Engineering supplier vendor.
I don't know if Horde can buy from him, I have bought a couple sometimes and sold at AH for a little profit )

This guy shows up as Alliance civilian. Horde can't buy from him.