I own the Printrbot MEtal Plus Dual and it has proven reliable and very robust. Printrbot has a very good support, they devise upgrades frequently and they publish very good techpubs : you can find on the support page an exploded view of all the components of your printer.

I posted a few prints here : http://3dprintboard.com/showthread.p...2027#post72027

Let me know if you have questions.