There wasn't obvious damage to the above-ground part of Qsoil.c, but it isn't responding. About 20min ago, I placed a spare Qsoil poking into the ground from above. It is reading fine (at 10.76%), but reports as ID29, rather than ID2A of the previous probe, so it isn't being processed correctly.
A restart of dsm_server now finds the new Qsoil.