Replicator model detaching

I've got the LUV Makerbot Replicator working, I will demo it at some meetings some time soon. One problem I'm having is that the model in progress will often get detached from the platform. The "Calibration Dual" model file that ships with the replicator has become detached three times, each time the front left corner lifts from the platform first and then eventually it all comes unstuck and the model is destroyed. I tried the "Cube Slide" model file that ships with it once and it detached when it was on the last black segment, so the model was mostly OK but it's still not a successful result. Any suggestions for how to deal with this? -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/