Remove the pump cover and sealing rings if not already done, then use a puller to take out the drive gear. Next, remove the rotor and shaft, lifting out the outer rotor. Unscrew and take out the oil pressure relief valve plug, along with the spring and plunger. Clean all parts thoroughly with solvent and check the mating surface of the pump cover for wear, grooves, and damage; if any issues are found, replace the oil pump with a new or rebuilt one. Use a straightedge and feeler gauge to check surface variation across the pump cover, comparing the measurement to the specifications; if it does not meet the required range, replace the oil pump. Measure the thickness and diameter of the outer rotor and the thickness of the inner rotor, comparing these results to the specifications and replacing the inner rotor if necessary. Install the outer rotor into the pump body, pressing it to one side, and measure the clearance between the rotor and the pump body, replacing the pump if the measurement exceeds the specified maximum clearance. Next, install the inner rotor and shaft into the pump body, checking the clearance between the inner and outer rotors; if specifications are not met, replace the shaft and both rotors. Measure the clearance between the pump face and rotors using a straightedge and feeler gauge, ensuring the straightedge lies across the pump face between the bolt holes; replace the pump if specifications are not met. Finally, measure the free length of the relief valve spring and compare it to the specifications, replacing the spring if necessary. Reassembly follows the reverse of disassembly, ensuring all parts are generously lubricated with engine oil and tightening the cover bolts to the specified torque.