Just had this happen. Could only turn off flow by turning off power at pull cord. Took it apart and noticed there was water in the on/off switch unit which must have kept the ON circuit open. Am guessing this is due to condensation over the winter (our house is usually freezing!)
So ISOLATE /POWER OFF at fuse board
Pull unit out
Mop excess water up with tissue and blast the unit with a hair dryer 10 -15 mins, all the while tapping the unit to dislodge any droplets inside.
Worked fine again for me.
:)
Ed
March 2026