I see this sometimes on long jobs when the heater block gets too hot and softens the filament PRIOR to entering the nozzle. It causes the filament to bend and not feed correctly. Once it cools off, it feeds through normally, so it doesn't really look like a jam, but it just fails to feed properly when it's too hot.
1. Check the fan on the right side of the extruder. It should be blowing INTO the extruder. This was changed between the first Press shipments and later ones to help keep the heat sink cooler. If it's blowing away from the extruder, simply unscrew it and reverse it.
2. Lower the temperature from the default of 230 to 215. This is dependent on the filament you use, but I've found my current filament prefers the cooler temperature and it keeps the heat from overwhelming the heatsink.
3. Open the lid slightly to cool it off slightly. I simply close the clear plastic door before closing the lid. This creates about a 2" gap so the chamber can vent. It seems to keep enough heat in that I'm not having layer adhesion or warping problems, but lets enough air out that the filament doesn't get too hot.
Nothing frustrates me more than to have something print perfectly for 5 hours, then glance over and see it "air printing". These three fixes have resolved 99% of these problems for me.
Best regards,
Ron