The soldering job on that red wire is none too good… 
Yeah, I’m afraid you’re right.
I checked it with a machinist square to ensure the nozzle was higher than the sensor or shroud (and it was, by a mm at least). Trued the X-axis linear module using 1-2-3 blocks on the Y-axis linear module rails, to the point where the plastic feeler gauge that comes with the unit was catching on both. Put the 1-2-3 blocks on the bed, and there is a .229mm difference from the 0 side of the X-axis to the 320 side. About what I was getting before (0,0 corner was about 0.3mm lower than the center).
Did an 11-point auto-level and used a .178mm feeler gauge to set te clearance.
Fired up a simple job, and the nozzle carved a deep gouge starting from about [50,50].
So yeah, this thing is hosed.
EDIT: So I got up and running. Looks like the gouge was caused by the setscrew not gettng tightened enough or somesuch - the hot-end had pulled out about a quarter-inch. Got it in correctly and calibrated the sensor as best I could give the marks from the original screw. Eleven-point leveled, set height to 0.178mm. Then put some painter’s tape down and did trial-and-error runs with a manual Z-offset override. When the bed was cold, the nozzle cleared at -0.5mm, and adhesion was good. When the bed was warm (50C), this was much too low, and I had to bring the Z offset up 80 points (which, interestingly, is just under the thickness of the ruler I was using) to +0.3mm. That’s a .8mm difference due to temperature.
After a successful 15-minute print, I am attempting the print that caused the problem yesterday: a filament guide. Watching it like an Australian Shepherd.
EDIT II: Found the root cause of the problem. After two hours, the print lifts off the bed, and encounters the nozzle. I caught it just as it was losing adhesion and paused the print. Had noticed early on that one particular corner was lifting, and it only got worse.
In regards to adjusting the sensor, I found this FAQ: How to adjust the probe proximity sensor in the 3D printing module. I looked all over for a maintenance/repair manual and came up dry; it didn’t occur to me to check the FAQ for this sort of thing. Usually an FAQ is questions like “is it righty-tighty or lefty-tighty?”.
I had a similar thing happen when mine clogged. Went through and CADed up a replacement. Dimensions are probably not perfect but I printed and installed it and it seems to work fine. There’s a little bit of deformation around the fan screws but they have been holding without problems.
https://www.thingiverse.com/thing:4836338