It's as though a glue bond has broken away after consistent and repeated use of the right hand resting on the lower right panel (which makes for a convenient handrest between typing/mousing pauses).
Has anyone had a response regarding this, and the best way of fixing the problem? Seems as though it would be a little trickier than removal of the back of the PB to get to the problem..
Had a reply back from the support guys who have offered the following:
The problem is that the glue bond on the bottom pan is very week and comes loose over time. You can either purchase a replacement bottom pan or glue the plastic insert to the bottom pan.
Not sure if this answsers it completely enough for me yet so will forward a photo of the problem spot and make absolutely certain, as I can't yet see how this involves the bottom pan.