CM870 Jake problem

[Nilao]

I notice when i have a vibration in my jakes it is becaise 1 stage isn't actuating. You have changed the harness and solenoids but have you inspected the rockers? They most likely need to be replaced with that many miles. The piston inside could be worn and sticking or leaking too much oil around them at operating temp...i believe you can remove the piston by taking out the adjustment screw but i have never disassembled one that far.

Also the rocker shaft itself could have too much wear....