This is just from my experience using the Titan and V6 on my Lulzbot Taz. Hopefully the info here will be helpful to others. If your Titan starts making clicking noises (usually after changing filaments) some would ascribe this to 'backlash' where the teeth of the gears are not perfectly seated. Yes that can happen, but that is not the root of the problems that I have been seeing on the Titan. The root of the problem is a minor deficiency in design (sorry E3D - I am an engineer, I'll make up for the unsolicited design critique with a potentially permanent solution). Simply put, the moment (i.e. force) created by the idler's spring is sufficient to slowly throw the larger gear and filament guide out of alignment with regular use. Proof of this is that even if you take the cover off the Titan to 're-seat' the gears while the filament is still inserted all the way to the V6 - and you put the cover back, the clicking/backlash will likely still be there. The temporary solution is to retract the filament, completely disassemble the Titan and MOST importantly make sure that the shaft of the motor is precisely at the center of the hole on the Titan's cover (which will be more difficult to do if the filament is still inserted). Once reassembled properly, verify again that the motor shaft is still centered. If so, the clicking noise/backlash should go away (at least until the next time you have to change filaments or do anthing on the Titan. You will notice that the motor shaft will slowly go off center with regular use). My design suggestion is to extend the center hole on Titan's cover such that it extends and meets up with the motor shaft, ideally with a Delrin gasket or more preferably a bearing added to 'fit' both together. Despite the fact that the Titan has 4 bolts to attach the frame of the Titan to the mount and motor, these bolts do not significantly counter the moment of the idler's spring - only the motor shaft is doing all the heavy lifting. This results in the repeated misalignments (clicking and backlash) after regular use. By adding a top end Delrin gasket or bearing, all of these recurring problems related to clicking noises/backlash on the Titan should go away permanently, since all 5 posts/bolts/shafts will then be supported at the top and the bottom. I hope this helps.