Sorry for spamming the thread but i can't get this to work properly.
The sensor calibration screen shows only half of the sensor screen, the one nearest the front of my cabinet.
When I pull out the plunger the top half just flicker gray to black and when the plunger passes over to the front portion of the sensor I see it change from black to white but the top half just keeps flickering!
Given that it's exactly half that's not working, I have a guess. The physical sensor is actually *two* sensors, each covering half the distance. They're positioned right next to each other to create the effect of one continuous column of pixels, but they really are two independent devices on the inside of the package.
So there are two main possibilities here. One is that you have something wrong in the wiring that's connecting the two half sensors. You should go back over the wiring diagram in the Build Guide and compare it to the wiring on your sensor, paying particular attention to the sensor pins that are wired to each other. Pins 2, 3, and 9 need to all be connected together, pins 7 and 8 need to be connected to each other, and pins 6 and 12 need to be connected together. Visually confirm that they're all connected, and if you have a multimeter, do a continuity test to verify that the solder connections are good.
The other possibility is that one of the half-sensors is broken. If you're certain that the wiring is all correct, and you're getting good pixel readings over half of the image, this might be what's going on. The good pixel readings on half mean that the wiring to the KL25Z must be good and the software settings must be working.
Hopefully it's just in the wiring. A couple of other people have had sensors that arrived dead, so it's not impossible that you have a defective one, but I wouldn't jump to that assumption until you're absolutely certain it's not the wiring. And I'd test continuity with a meter before deciding the wiring is good, since it's really easy to have a solder joint that looks perfectly good to the eye but isn't electrically conductive.