So, it must be touching something. Quick glance shows only a few flexible cables in the way. My magnifying glass tells me that the cables are good. No break in the insulation. A look at the cover.
Lets have a feel of the surface.
Now it decides to bite me. So, this is another of SONY's excellent marketing plans. If the consumer opens it, cut him. A piece of paper between the razor edge and the cables fixed that problem. So, that was the end of the saga.