Since the Wiki is down, I can confirm that you need to complete One Bad Mother (quest trigger item drop from infected leader) in order to get Gadget Boy to show the quest. I completed all of Gadget Boy's and Turu's other quests and quests from the Argent area before activating the infected leader drop. As the post above me details, you can complete Qularr De-Fleeted and then the Schematics of a Monster quest should appear on Gadget Boy.
Comments
Much appreciated if you do
Do all Gadget Boy quests.
Do all Dr. Toru quests.
Kill Infected Leader, get drop, start new chain.
I don't know if the Infected leader drops the quest before you do the chains, but feel free to try.
All of this is over in the same area, near the Qularr mothership/digsite.
Ok that led to the mission One bad mother which unlocked the Qularr De-Fleeted for me, which then unlocked Gadgetboys next chain of missions.
Thanks a bunch