Torque of Multiple and Different Sized Fasteners: First tighten all fasteners by the help of free hand. Then torque big fasteners first followed by torque of smaller fasteners in criss-cross pattern from inner to outer to avoid any distortion in the assembly parts.
Oil Seals: New oil seals to be installed with multi purpose grease packed into the cavity. When installing seals always check that the shaft over which the seal fits is smooth and free of burrs, which could damage the seal.
Old Gasket and Sealants Removal: Old gasket and sealant material should be completely removed before re-assembly.