So I shelled out 150 bones for an i3 clone on ebay. I know all the haters are going to say I should have bought a better one, but here we are.

First print the thing works like a champ, I download a file from thingiverse, slice it, and presto bammo we are printing. Not perfect, but not bad for a first run.
I take a swing at a second print and start having extrusion issues. I could hear it clicking and assumed the cheap, plastic extruder that lacked any sort of spring tension was the issue. After disassembling and reassembling a million times the problem continued to get worse and worse. I started to notice the stepper for the extruder wasn't running properly, and eventually not at all.

I have tried the following to narrow down the problem and am still stumped:
Connected the extruder stepper to the x axis. It works fine.
Swapped the drivers around. Both are functional.
Checked the reference voltage. Also acceptable.
Swapped the cables to the stepper motor. Also functional.

Anybody have any ideas as to what might be going on? This was a very progressive issue and worsened gradually until the motor was inoperable.

Thanks in advance guys and gals!