Using the diagnostic test 97 (see https://www.applianceblog.com/mainforums/attachments/krfc704fps00-tech-sheet-w10832390-rev-c-pdf.37841/ which failed to produce water, it was clear it was either the ice maker water valve or the valve heater. Replaced it by pulling out the old one (tie a string to the end to make pulling the new one easier) with a plier down into the ice compartment - some force required.