Print Fails at same pont ...

Our Replicator 2X was working pretty well. However I've tried to print this object many times. Each time changing things like print speed, extruder temperature, etc based on some other forum posts I read.

The object is : http://www.thingiverse.com/thing:39751 , the Rim w/ Support...

In prints very well until we're about 3/4 done right when it starts to print the flange. Then the extruder seems to strip on the filament. I unload, clean out, and reload... Things print again fine... then I try this Rim and it fails within a few layers of the other failures.

Anyone have any suggestions? Could it be a flawed model?