Oscillating Material Feed Stepper Motor

My 3D Printer has suffered from Oscillating Stepper Motor which although rare seems to have occurred to other RepRap style Printers; when the stepper motor which feeds the material into the Print Head repeatedly changes direction, causing no overall movement of material, and preventing printing. At first, I thought this could be a loose connection in the mother board and general circuitry of the 3D Printer, but after checking all the wiring and connectors, this was eliminated. I then though it was a software issue, sending a corrupted signal. However, after great research I am still unsure about the root of the problem. One option, which I was reluctant to follow, was to reformat the 3D Printers software. Another idea, because my Printer is a dual extrusion model, with two Print Heads, thus two feed motors, was to swap the connections, so that the second motor would take the first motors command and feed into the fist extruder. Although a short term fix, it worked; so the problem isn't software related but must be in the stepper motor, or its wiring. Before progressing any further I will contact the manufacture, to enquire, and potentially get a replacement stepper motor, to solve the issue. Up un to now, I have had very little hassle with the general running of the 3D Printer and it has enabled me to develop my CAD/CAM skills, especially in design preparation for additive layer manufacture.

I have experienced this problem again today (02/07/2015), this time both stepper motors oscillating instead of rotating when sending the manual command to extrude 5mm of plastic. I fixed the problem by removing the stepper motor connections from the circuit board of the printer and then reconnecting them, checking for any loose connections.

3D Printer Hotend fix.

I experienced quite a catastrophic printer failure today, when the temperature of the Hotend (the component which the plastic filament passes to become molten before extrusion) raised rapidly to 250°+ causing the carbonisation of the PLA material. After quickly shutting the printer down, and increasing ventilation to clear the burnt plastic smell I investigated the cause of the failure. The thermostat had disconnected from the main heatsink of the Hotend, which meant that it was heavily under-reading.

After some research, and much thought, I worked out a process to reaffix the thermostat to the hotness. Simply glueing the thermostat back onto the Hotend, could potentially effect the sensitivity of device, and was the original fixing method. (Which evidently failed) Therefore, I decided to use wire to tie the thermostat to the Hotend positioning it onto the heatsink, providing maximum temperature accuracy. Only a small job, but without accurate temperature control, successful prating is almost impossible. I considered the effects of heat conduction though the wire tie, but decided that this would be insignificant and would not cause any harm to the cables as they all have heat resistant outer covering.

I attach two images of the Hotend in my printer, with the wire fixing holding the thermostat in place.

Disassembly of the PrintHead, notice the thermostat
and circuitry (on LH Hotend) disconnected from the Hotend.

The insulated cabling tied to the Hotend, holding the
thermostat onto the Heatsink for optimal reading accuracy