I have an idea. Send one to me and let me play with the problem. I'm not kidding, I'm interested.
Suggest installing Linux 12.04 in a spare caddy. It will run in anything (any CF-19) and there are a couple diagnostic things you can try. W7 is so secretive about what is happening behind the scenes.
Meanwhile...is this the same W7 caddy switched between machines? The calibration numbers are hidden in the registry somewhere...the only thing you can do is check the re-set box on the calibration page to zero them out and start over for each unit unless you know where the numbers are stashed.
Teo, Is this new with the MK3 panel? Just one has a problem or more than one? Did they change the length of the circuits maybe....maybe change material?
Jacob, Can you check a MK3 and MK5 at the same time and measure resistance for 1/3 2/4 on the TS FPC? No particular number here. One circuit will have higher resistance than the other due to circuit length. (In my limited experience) I'm wondering if there is a significant difference between the TS panels in the MK3 and MK5.
Another weak point is the connector on the TSPCB. On CF-19! See a post by Morgan re: building up the thickness of the FPC cable end. And always tape very securely.
That's what I get for sleeping for twelve hours. Ideas are popping.
Wait, you're dealing with closed lids, yes? That idea just popped out. All of the above was concerned with a situation where the lid is off and the TS FPC un-plugged from TSPCB.
So in your case this is multiple lids on multiple lowers or one lid on multiple lowers? If one lid blame the lid and check the TSPCB connection in the lid.
Try MK3 touchscreen driver? I noticed today that MK4 is using a Wacom Finger Touch (in a Multi-touch unit) so if MK3 is Fijitsu and MK5 in Wacom...where does that take us?
Swap the TSPCB from the donor to the receiver?
Does this make sense to anyone? Don't answer that.
Jacob, Rob has my cell number if you need clarification. Remembering that confusion and clarification start and end with the same letters.

(I just made this up)
Jeff...drinking coffee at midnight...