Because of the need to perform extensive work on the valves, valve seats and valve guides, often referred to as the 'valve job', it is advisable to seek the services of a professional technician since the job calls for proper alignment and use of some specific tools and equipment. A home mechanic can take off the head, scrape, clean as well as assess the valves, then reinstall the head and bring or take the head to a dealer service department or an automotive machine shop for the real servicing of the valves. Some of the duties of the dealer service department or the automotive machine shop will include the removal of the valves and the springs, the reconditioning and or replacement of the valves and valve seats, the inspection, reconditioning, and replacement of the valve guides, the checking and replacement of the valve springs, the spring retainers, the keepers as may be deemed necessary, the replacement of the valve seals with new ones and the reassembly of If the surface of the cylinder head gasket is twisted then it is also refinished. After the valve job is accomplished by the professional the head will be in good condition as if it was when it was new. On its return it should be again washed to remove all the particles of metal and other abrasive materials which could be left following the valve service or the process of milling or facing of the head and if possible all the oil holes and passages should be blown with air.