well, I've been considering myself lucky that my original J-Head had been working reliably. Tonight, while experimenting with leveling, I typed "G2 Z2" instead of "G1 Z2" and the effector went skittering across the glass, slammed into the X-Z bed clamps, and I quickly shut it down. After that, it would do things like G28 and G29 but it would not do a G1 - said "printer error ..." Closer inspection - the thermistor wires are broken clean off, and the potting compound holding the thermistor is chipped and broken. Now what? Try to repair or move on to K-head? (I don't even know what a K-head is honestly, except that it comes after J.) Will the effector work with it or are modifications required?