No special maintenance is needed in the power brake unit, except that the hoses should be inspected periodically, as well as the air filter below the boot where the pedal pushrod enters. Power brake unit dismantling requires special tools and in case of any issue then it is better to change the unit of power brake with a new one or a factory change unit rather than trying to overhaul the existing booster. In order to start with, loosen up the mounting nuts, which hold the master cylinder to the power brake unit, unplug the connector of the brake fluid level sensor, and put the master cylinder in place without over straining the lines. In case the lines are doubtful of flexibility, disconnect them at the cylinder and plug the ends. The second step would be to un-hook the vacuum hose to the front of the power brake booster and seal the end of the hose. To access the under dash blower air duct, inside the vehicle, remove the split pin, and clevis pin to unattach the power brake pushrod to the brake pedal but do not force the pushrod to the side. Then place the four booster mounting nuts aside, and then lift the unit out of the engine compartment with great care. To install, loosely fit the four mounting nuts, pushrod to the brake pedal, tighten the nuts, and re-fit the vacuum hose and master cylinder. In case the hydraulic brake lines are not connected then the whole brake system must be bled to remove all air which can have found its way into it.