I've been trying to get this to print in pla for months. But it always jammed about 30 minutes in.
Updating from firmware 5.2 to 6.0 (at the suggestion of Makerbot support) seems to have done the trick!
Ultimately, though, I believe the problem was two-fold, the extruder was not firmly gripping the filament, and the ambient temperature was high enough (either because of the weather or the shroud I use) to make heat creep a problem.
In prints with more continuous extrusion this isn't as much of an issue. But this print is lots of tiny circles leaving each bit of filament in the extruder much longer, and increasing the likeliness that the PLA will degrade/jam before being melted and extruded.