My drain hole and filler vent hole are on the starboard side of my
Evinrude...the vent about 8 inches above the drain/filler (which is just
below the prop housing).
My manual says to put a container under the lowest screw and remove it.
Then remove the 'vent' screw to enable the gearcase oil to flow out.
To re-fill, I take the small jug of gearcase oil and stick the tapered
nozzel into the lowest hole and squeeze until oil starts to flow out of
the above 'vent' hole. Then I quickly screw upper 'vent' plug back in
and lastly, screw the lower drain/fill plug in.
A tad messy...but I hope to get better after a few changes.
Manual says you can simply re-fill from top 'vent' hole...but you have
to be careful of air bubbles.

I don't get a good mental picture of how this is being done. I really
need to get a copy of the outboard engine owner manual, and then come
back to re-read your instruction.

Thanks.

Jay Chan