Stopping an electro magnet clutch from sticking

I have a Dorman 747-300 Sliding Door Motor for a Dodge Grand Caravan.

The motor has a magnetic disc that will engage a brass "Clutch" with motor to open/close the door automatically. When the door is manually operated the clutch is to be disengaged from the motor and allow the door to move freely and not "fight" against the motors gears.

The problem is that the clutch is stuck to the motor gear and therefore makes it difficult to operate the door manually.

I have disassembled the part and cleaned the mating surfaces and relieving any suction/attraction that the parts have together. This allows for "free" manual operation, but it does not last long. After the door is used with the automatic button and the motor is used it gets "stuck again. Any way to remedy this sticking?