Repairs John Deere LX280 PTO Question

My electric PTO broke the pulley last year so i installed a new JD AM126100 PTO and the tractor was fine for about 10 hours of use.The problem is that when i disengage the PTO it make a grinding noise and i can see that it is the clutch that is hitting the pressure plate does any know if there is a adjustment because the old PTO made the same sound and i don't want another failure for $150 again.This unit does not have any screw adjustments on it but i know on a a/c compressor on a car witch is the Basically the same design i was able to adjust the air gap and solve the grinding problem.