You start servicing the valve guide seal and installing new valve stem oil seal and valve spring by first removing the valve Rocker Arm covers. You need to turn the engine to reach top dead center in the currently worked cylinder to make sure no valve drops in. First take out the Spark Plug then unmount both valve Rocker Arm and push rod. You should place the Spark Plug port adapter (J23590) in the Spark Plug hole and divert compressed air to maintain valve closure. Set the valve spring compressor (J38606) on the valve spring, activate it to compress the valve spring, and take out all parts including the valve locks, valve spring, cap, and valve stem oil seal. Check the valve spring for damage and purchase a replacement if it needs replacement. To mount the new oil seal gently push down the stem until it touches the valve guide without applying force on the tool. Use valve stem seal installation tool j42863 to push the valve stem oil seal over the valve guide. Set the valve spring compressor (J38606) back on the valve spring then push the tool down to compress it. Next install the new valve spring and cap before placing valve locks in position correctly. Drop the valve spring and take out the Spark Plug port adapter (J23590). Install the Spark Plug afterwards. Put back the valve Rocker Arm and push rod before putting the valve Rocker Arm cover(s) on top.