I have a very well maintained Legend SE. Last year the bypass started to leak after shutting down the machine. After several trips to the repair shop and replacing all possible parts the bypass won't shut off.
Lay a steel object on the top of the solenoid with the switch turned on. If it sticks you have a sensor issue, if not it could be trash inside the solenoid. But don't forget to check the manual dump valve it could be that and not the solenoid.