I get clicking whenever my bed is out of whack on the Davinci. It's when the head won't extrude. Check your bed alignment, and if it's ok, then it's probably the PLA, as that extruder head isn't designed for PLA.

On the voltivo forums, I had suggested and described a water cooling system to prevent this. A lot of people said it couldn't be done, but then somebody else went and did it. So if you have the means, place a water cooling block where you want the heat to stop. That should prevent the heat from creeping up the head.