When the machine travels rear to front, the front arms should retract using the front arm return solenoid. While the gauge setting is 60PSI, it will usually be set a little less than 60 as normal return pressure. There is a small flow control valve used to soften the retract so they don't slam in the outward travel. They should retract softly against the out bumpers.
The other things that could affect the retract would be more mechanical with either the arm leveling, or possibly binding in the air cylinder. On each cylinder, there is a clevis pin. It should be clean and lubricated monthly so you can manually shift that pin up/down. To level the arms, turn off the air to the machine, then use the manual dump valve off the bottom of the MAC panel assembly to drain air from the system. Move one front arm to their fully "out" position against the out bumper, pull it out about an inch and let go. It should remain fairly steady. Then, lift the top brush out of the way, and bring the arm to the fully closed position against the bumper. Move again about an inch and let go to see if it moves. In both instances, it should move only slightly or not at all. If it does move, that indicates the arm isn't level. To adjust, you will need to put a floor jack under that brush, loosen the arm pivot bearings and adjust until you can keep them from either falling towards the center, or outward. It's OK if they move a little during this test, but it should be very slight and slow.
