Right, the design is similar to that of a reprap.
The nozzle is heated by a heating element that is wrapped with fiberglass. Be careful if you're handling the fiberglass, you don't want to touch that too much or esp inhale the broken fiberglass dust.
The way to get to the heating element is to pull off the blue sheath. You'll then see the heating element, a thermsistor, scantily wrapped in some kapton tape to hold it all together.
You can't use any reprap thermsistor since different thermsistors have different characteristics and may (or may not) need reconfiguring in the arduino firmware, but any reprap friendly heating element should work (if the heating element is indeed what is broken). It's going to be a pain putting the blue sheath back on, especially since I've done this a couple times already and the fiberglass is getting worn down. I suggest contacting someone (Miloh, Jake) at TypeAMachines and asking them for a replacement part and tips. Watch out for that broken fiberglass!!!! Also, you definitely want spare kapton tape for this operation.
Before you take apart the nozzle system though, definitely make sure that voltage is going through, probably using a voltmeter. You can take off the wooden plate on the left side of the machine to get access to the electronics board.