nwtadad

My 07 F150 intermittently will have the grinding noise of a failed actuator on the driver side. By engaging the 4x4 selector switch then disengaging it, the noise goes away. It could happen couple times in a week, then not at all for an extended length of time. It always goes away when cycling through the 4x4 engagement. The truck does have the newer style solenoid valve with the plastic house over the solenoid.
Suggestions where to begin the search before winter sets in?