This thing is going to be a BITCH to put back together.
Anyway: before I put it back together I plan to take some pictures to illustrate the problem, which is the flex print header that connects the KLM-2725 board to the touch panel, as illustrated in the video http://youtu.be/WIs9OPKYspY (albeit not clearly)
I have a theory about why the Zero 8 is prone to this problem. It has nothing to do with heat. Simply put, users are inclined to slide their finger around the touchscreen, which actually causes the bezel to move very slightly, relative to the board. Eventually these fractional movements cause that fine-pitched connector to become misaligned with the flex cable it mates with.
The solution would either be a slightly longer flex print cable, or a connector that grips the flex better, or otherwise soldering the flex directly to the board.
FWIW my Zero8 was previously serviced by the dealer for this very problem. (This could explain why my mixer has screws in places where others don't)
EDIT:
After some thought I think that another reasonably permanent fix would be to apply a small amount of a suitable adhestive inside the touchscreen flex connector. The connector housing itself does not seem to provide enough friction to secure the flex ribbon in place.
I am attaching a picture to illustrate what I'm talking about. Here you can see the touchscreen connector (brown/black), and the t-shaped flex cable end which is inserted into the connector has clearly become misaligned. In the picture it is obvious that the cable termination is not parallel with the edge of the connector. Once I disconnected it and put it back in straight, the touchscreen started working fine again.
