So I’m on my 3rd hotend v2. and this one has the same problem. Made a beautiful print. Made anotehr print. Went to extrude plastic for a third print, and the thing is clogged again. I’ve been doing cold pulls for hours. The gears are chewing up the filament. If this problem persists, I’m sending this thing back. Last time I resorted to trying to get the nozzle off, and it stripped inside. I’m going to continue to do cold pulls and hope this works. If not, forget the taz5. there’s something wrong with the tool end, and I’m geting fed up with having to send it back. Suggestions please.
I’ve had some problems alike. Similar but not quite, for me there were several causes at different times.
1: make sure that the (Small Fan) is always on and is facing directly at the heat sync.
2: make sure that you have the right amount of tension on the idler springs.
piercet - “the idler arm tensioning screws to be about 8mm”
https://forum.lulzbot.com/t/enclosure/1773/1
That’s all i can think of initially, that forum thread goes a little more in depth about nozzle clogging; (with an enclosed machine) but the cause an effects of clogging are quite similar with / without an enclosure.
A couple of things to check:
Make sure, when the idler bearing that pushes the filament against the hobbed bolt is swung completely away from the filament, that it spins freely. When my TAZ arrived it didn’t, I found small shreds of support material from when the bearing carrier was made in the very small gaps around the idler bearing. Cleaning that out so that bearing spins completely freely is critical.
Also, it’s my practice to wait a few minutes after the extruder is up to full temperature before beginning a print, to allow the heat to spread through the entire nozzle area before starting. I also always do a couple of 10 mm extrude operations into the air, with the extruder 50 mm or more above the bed, before starting a print to ensure everything’s running smoothly.
I successfully removed the nozzle and replaced it with a .3mm nozzle, and the original nozzle is now soaking in acetone, with me using the dental pick to remove what I can everyonce in a while. I’m 4 hours into a 9 hour print and it looks absolutely amazing. I had to change the slic3r configs a bit, but all is well, and I now know how to remedy this situation if it happens again, and Also have nozzles from 1.75-5 that I know will fit. Will the other ones print? Time will tell, I will keep everyone updated 
Where did you find the smaller diameter nozzles? I’d love to try a nozzle smaller than .3mm.
Scott
Reprapdiscount had 1.75 and 3mm hexagon kits and i bought those. And makerbot has 3mm nozzles. I don’t know why, but the 1.75 from reprapdiscount says ‘4’ on it. Regardless, I had the makerbot ones open and it worked flawlessly. Just finished an 8h25m print