I see there are plenty of threads dated around 2015 associated with the K8203 extruder kit jamming, but nothing since. I upgraded a couple of months ago & have had a couple of jams where the filament gets stuck in the hexagonal shaped piece at the bottom of the extruder, leading into the hot-end.
My guess is that the spring on the driver is too strong, flattening the filament as it passes through, causing complications during complex bits of printing involving a relatively large amount of extruding & retracting relative to actual printing.
Anyone else experiencing this? I’m going to try a different filament type, a looser spring (as suggested in previous prints).