John deere 310G park brake problems

I have had a hell of a time with my 310G s/n to310GX934593 park brake everything works fine on the machine except when the machine is driven for a short distance and park brake is applied then a buzzing sound is heard and is coming from solenoid area below the steering wheel column. I replaced all three solenoid pressure switchs witch are outlined in red but still have buzzing and the buzzing seems to be coming from that area
if I disconnect the X27 solenoid connector the buzzing stops but...

John deere 310G park brake problems