@Notepad All new wiring on the 1LC to BL Touch circuit (new connector ends, etc.). I even tried moving the probe back on to the mainboard:
M558 P5 C"!io2.in" H6 F240 T6000 A5 S0.03No, I did not attempt the R-delay on the mainboard. This had been an original setup for me, io2, until I got the 1LC toolboards. I was reaching the point of getting out my pocket scope and look at the supply line noise. BTDT
I'm happy that the error went away, suddenly. The only other time I've seen this was while working at a company next to a laser crystal manufacture (read: elecric furnaces). End of the month, our development computers, mysterously, stopped working (no bootup). Doh! Took us a while to figure that out.