Quote Originally Posted by Geoff View Post
Are you printing in PLA or ABS? if it's PLA possibly the same as Roxy happens to me alot, if I leave the PLA on the machine, over time it heats up and expands inside the tubing, making it around 1.8 to 1.9mm thick, which causes me major jams. The way I got around it was just don't leave it loaded when im not using it.

In your case however, it's happening while you print, all I can think of is that your code isnt fluctuating the heat levels depending on what it's doing, and if it's running at full temp all the time, this might also make the plastic go a bit squishy inside the tubing, simply from heat running through the filament all the way through it. I've noticed on the firmware im using at the moment the temperature changes depending on what it's doing and rarely does it print at the full max temp for a long period, it always drops it a few degrees for slower shells.
You should try the E3D hotend, I had the same problems with PLA and after changing to that one they are gone. I think the combination of a large heatsink and a very narrow stainless steel "neck" between the hotend and the heatsink makes a very sharp transition between the melt area and the filament, when I change filaments I can see that the transition is about 2mm only.