I have a Delta printer with Bowden extruder and all-metal hotend. When I start printing, the hotend gets often jammed. It seems to be independent of the print I am currently doing. Retraction does not affect it either (it happened even with 0 mm retraction).
However, despite occurring mostly at the start of the print, it also occasionally happens mid-print.
I can resolve the issue by pulling the filament out and after few seconds putting it back in only for it to happen a couple lines afterwards.
At this point it seems to me that heat creep is most likely, in spite of having a 40x40 mm fan blowing across the fins of the heatsink.
Is this heat creep? If not, what could be the cause?