Because of the nature of the job and the more so owing to the use of sophisticated tools and equipment for the task, valve job that essentially involves resurfacing of valves, valve seats, and valve guides should be left to a professional. A home mechanic can remove and strip the head, usually do primary cleaning and examination and then bolt it back for delivery to a dealer service department or auto machine for the actual work to be done on the head. Carrying out the exercise enables one to have an idea on the state of the head and valve train subassemblies, work to be done and new parts when dealing with an automotive machine shop. In the dealer service department or automotive machine shop, the valves and springs will be removed, reconditioning or replacement of valves and valve seats, reconditioning of valve guides, check and replacement of value spring, rotators, spring retainers, and keepers as may be necessary, replacement of valve seals, reassembly of valve part and ensuring of the correct height of installed spring. Also it will be necessary to lightly machine the cylinder head gasket surface if it is warped. If the head were to be worked over by a professional the valve job would restore it to its near-new state. On its return, it is required to wash the head again prior to fitting to the engine to remove any of the steel particles as well as abrasive dirt that may still be in the head following the valve grinding or the resurfacing of the head as may be necessary using compressed air to blow out all the oil holes and passing.