Curling/warping only around extremely tight corners (not exterior perimeter)
As the title suggests, I'm getting curling/warping only on very tight corners. I'm getting fantastic bed adhesion and for the most part my prints turn out wonderfully, and as mentioned in the title, this does not happen on exterior perimeters, so far only on very small internal pieces like thin rods and the smallest circle of concentric infill. What appears to be happening is the placement of the cooling fan is such that printing things in certain orientations will cause one small area to not get cooled, and ultimately the warping becomes so bad at that one specific spot that the print head eventually hits it and shears it off.
This happened to me twice today, once while printing a one-piece wrench and again last night while printing a headphone stand (both from Thingiverse). The latter had concentric infill on, and got 11 hours into the print before the inner most circle of infill experienced the same thing and was sheared off somewhere during the print. It kept going for a while longer until another small circle of infill did the same thing.
I tried slowing down my small perimeter speed in Slic3r from 20 to 10, I'd be hard pressed to say whether it had an effect though. Short of using a different infill, which is an option for the latter print but for the former it was actually happening on a piece that wasn't infill, what options in Slic3r can I toy with to give those tight corners time to cool?
If any more info is needed please let me know. I'm generally just using close to default (Prusa) settings in Slic3r Prusa edition, using Hatchbox PLA+ on an i3 MK2S. I guess it's worth noting that I'm using the profile for Prusa PLA, but it's worked fine otherwise.
Apologies for no pictures, my prints were so utterly ruined at those specific points that there's actually nothing left of the circles. If I print anything with the same issue I'll update this post.