How is a J-Head Extruder Head attached to the Prusa i3 rework? I am building a Prusa i3 Rework, and I haven't been able to find out how to attach my J-Head extruder (see below), at the moment it's just kind of held there by pressure, but it seems there are two holes on ether side of it; not sure if they're meant to hold it in place, but it seems that way.  



Any suggestions as to what I should use to hold it in place?  This is definitely a part that gets moved around alot.

update
It looks like the hotend may not be all the way in, are you sure it's not stuck?

If it's stuck and you can get it in further, those holes should go directly through the smaller ring on top of the J-Head.  You just need to run a machine screw into each hole to secure the hotend. The screw will need to at least be flush with the other side to work correctly.