I have been tinkering on this for weeks now and the biggest conclusion i can muster is it has to do with the IC Control Board soldered to the Digitizer. If you are ordering them pre-assembled the solder joints are likely shorted together, i have been able to fix a few by changing the IC Board. I have had the tape along the bottom work on one but that was the only one. I would love to work with somebody to nail this down hit me up.
btilleyster@gmail.com