Have you had to tweak your retraction settings? I recently got a series 1 and I've been having issues with grinding at the extruder pinch roll, and it coincides when there's more retraction going on. It's not wearing a flat spot in the filament, but it's like the filament gets hot on the entry side of the hot end and deformes making it not fit when it tries to extrude again. Odd thing is that with clear PLA it works just fine, but when I change to a color the problems start. Just curious if you ever encountered something similar? I've tried printing all the way from 200-245C with the same result.