Tevo has released their new Titan Extruder kit.  This is a great Titan Clone by Tevo, and comes with their latest printers. I picked one up, and here is an affiliate link if you want one as well. 

AliExpress.com Product – 3D printer parts TEVO Tarantula Titan Extruder Fully KitsTitan Extruder for 1.75mm 3D printer extruder for J-head bowden

Here is a replacement Hobb and Stepper motor gear. This seems to be the part that causes the most problems with breakage, and needs replaced.