Yanmar 2GM Oil pipe replacement

I've been chasing slow oil leak from rear of the engine. I've replaced that valve cover gasket and the lift pump. My next try is to replace the oil pipe that supplies the rocker arms.
It is shown here:

As you can see three types of copper gaskets are used. One 8mm gasket is thicker and goes against the head, P/N 104884-59170. The other 8 mm gasket is P/N 23414-08000. The two 10 mm gaskets are P/N 23414-10000.  The oil pipe is P/N 128270-39200 along with a new tie down clamp P/N 124450-39420. The parts cost was about $40.

The starter did have to come out to get the new oil pipe installed. The oil pipe routes behind the starter near the engine block. time will tell.