To put it slightly differently than my first post about this, as there were no responses.
I have followed the directions from the Service Sheets regarding primary drive oil level.
If I remove screw M (the second screw back) which is identified as serving as the level plug, no oil comes out even if I overfill it.
If I remove the screw behind that, it drains pretty much the entire amount that I put in.
Other than draining the case and then putting in a measured amount (1/4 pint) every time, I am unable to check the level.
Can anyone advise please?