Ok, so this is my printer and a close up of the dual extruder. In an effort to get a handle on all the various names of things (so that I can be consistent when I ask for help) ReplicatorG calls this a Replicator Dual. I believe that is a Makerbot Replicator 1.0 with dual extruders.
The Extruders look to be Mk7 StepStruders. Shown without filament being fed in because I’m debugging my lack of filament progress. Would love to hear someone who is more knowledgeable about the variations confirm or correct my understanding. I asked the support folks at KarasKustoms about (http://blog.karaskustoms.com/2013/06/makerbot-replicator-2-extruder-upgrade.html) but they don’t think it is compatible with my extruders.
You can’t really see but there is no way to adjust filament tension as far as I can tell. My current plan for debugging is to take the fans off one and verify that the stepper can pull filament through. (not have it go into the nozzle, just pull on it.) And to use my temperature probe in the nozzle hole to verify nozzle temp.
