Recently, the ticking sounds started to come from feeder of my UM2. Inspecting it I have noticed that once in a while stepper motor jumps back for few steps. I have an idea of what can be the reason, but I just want to hear what you can think of. That is the video of feeder during the printing :) https://youtu.be/z6CzudMOeD0 First tick at 10sec
I had the same issue. It can happen for number of reasons. One of them is too low print temperature as stepper cant push the filament through. Also you could have partially blocked nozzle or if you print with PLA and have left it out for a while its diameter can enlarge and get stuck in the bowden tube.