Working with a Makerbot rep 2 with glass build plate, and use matter control as my slicer.

No matter what temp I run at, every time I print, it fails within a centimeter of build height (z). It just stops extruding! Even when I push the filament, it won't budge (while printing) but when I pause the print, I can do the change filament command, have it act as if I am loading, and one big plush to the filament, and it extrudes again!. Until, of course, I unpause the print. It usually prints one or two layers, and stops again. That, or it doesn't do anything at all.
I have the speed set to 0.80, the feed set to 1.13.
Pictures of recent failed print, at 185. Did the same thing at 190, and 200.
[imgur.com]

Anyone have any good idea why? I have a new feed gear on the way, but I don't know if that's the issue.

Edited 2 time(s). Last edit at 06/25/2015 02:16PM by MegaRocketPenguin.

Heat creeping up from the hotend?
(Is there a nozzle fan?)

A gap between nozzle and heat break where a plug of soft filament is forming?

Too much retraction pulling soft filament up the heat break?

-a

I've taken that into consideration, and I don't know.
Its one of the three: Heat creep, Software issue, Extruder issue.
Definitely no gap. I've taken it apart four times in the past four days, and each time I make sure to screw in the aluminum tube first, then screw the nozzle in,back out a few turns, screw the aluminum tube in until it hits the nozzle, then lock the heat block into a vise and tighten the nozzle in with the correct torque. Each time I take it apart, there is no trace of filament between the two.
The retraction was set at 1mm.
Someone told me to stretch the extruder spring a little, and my first successful print literally just finished.
However, this doesn't mean anything. In the past 6 days, I have had three (Counting this one) successful prints.