When I print a model with ABS and rectilinear-filled top/bottom layers, AND that has many long runs of fill, I end up with something like a banjo on the bottom layer. All other layers are fine.

The problem has persisted even after I reversed and redirected the HE fan airflow (which did significantly address warping problems).

I'm printing with the default MF extrusion multiplier and width settings. First layer HE temp is 240C, and 235C thereafter..., the bed is 110C on all layers. FWIW..., I have experimented with HE temps around 225C, but not much changed wrt this problem.

The default first layer extrusion width setting is "200%", and I'm wondering if "300%" might be worth trying.

If you have any thoughts to share regarding diagnosis and "cure"..., that would be great. Note: the photo pre-dates the HE fan reversal fix, so it exhibits the warping problem..., but the banjo problem shown has remained the same after the fix.

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