Speak to Sergeant Dontrag inside the Deep Reaches in Stonetalon Mountains.
I've been waiting on parts for these guns for days! I sent one of my best blastgineers and two dozen miners into the Deep Reaches five days ago for the parts. After not hearing from anybody for three days I began to get a little worried. The Overlord sent two of his best orcs in to see what was going on. We've received no reports since then...
Head into the Deep Reaches, directly below this fortress, and find out what's going on! I need parts!