Oil Leak at front case half bolts...

Magnetic plug needs no washer. As shown in picture there is some metal washer showing.

I think this washer leakage the oil.

Remove the washer from magnetic plug.

The seal for that bolt is an Oring located at the case seam.
The tighness of the bolt has no effect on the Oring sealing.
Loosening and retightening the bolt may re-effect the seal but the Oring may just be deteriorating from age.

Assuming that splitting the case to replace the Oring is out of the question...
Pull the bolt and apply some silicon gasket seal on the shaft and reinstall.
Or, swap out that Split Ring Lock washer for a copper sealing washer.
Or, Both.

I agree with the above post. Remove the crush washer under the mag plug. It does not get a washer and is a metal to metal seal. This may easily be where the oil is coming from.

Okay, okay the crush washer is coming off at the next mag plug check.  The leak started before the mag plug washer was installed, as an experiment. 

Roger, I used your spray foot powder trick and it was definitely the top main crank bearing case bolt leaking.   

Does that bolt have a different torque because of the special job it is doing?  

Jeffrey, looking closely at your picture...  It may be just a photographic illusion, but it looks like there a crack in the case next to that bolt hole, starting about the 9 o'clock position of the bolt, continuing around to the 6 o'clock position, and then straight down for a little ways...