I'm having intermittent feed problems, where it runs fine for a while, and then starts to fail to feed the filament. I've confirmed there is no tension on the reel and even if I push a bit on the filament line, it doesn't help. The line is not broken either, as I can reverse it out. When I do remove it, there are no unusual grind marks on the filament - just the normal indents, so I don't think it's being stopped after the feed wheels. When this occurs, the layers are either missing or rather sputtered, as if it was 20-30% fill, even though I'm using 100% fill. I also using PLA. When this occurs I get a "clicking" sound about once a second from the area of the filament feeder. I can also see that the spindle from the filament stepper moves a touch but doesn't actually turn (it has a notch that is easy to view). I don't think it's a case of the pully that is mounted on the stepper spindle being loose as it seems firmly attached. Now if I stop the print, and start over (or even with a different object), it starts out fine, but after 7 layers or so (not consistent) it starts to fail. It's sort of like the stepper runs out of power after a while. Room is not hot (70F). In one case it took 5 hours (of a 14 hour print) to start to occur, and another only 10 minutes (of a 45 minute print). Any ideas what might be going wrong? The attached image is not great - but the left print has the top half layers sort of "porous" while the right one came out almost ok (the top most layer or two are not perfect). These two are a slightly different designs. I made one other print between them that started to fail at the 2nd or 3rd layer and I stopped it (not shown).