Finally I got around and took the clutch cover off to access the glass from the inside. Impossible! There is no way to access or apply pressure from the inside to press it outward due to the internal design. I have determined it is pressed in place from the outside. IF you have to take it out to replace I'm pretty sure you'll destroy or damage it, so be best to order a spare online from a Vintage cycle supply store. This Yam part is decades old for many older bikes and is roughly $15 as opposed to say Revzilla at +$60. Since it is pressed in, I took a long socket the same diameter as the rubber ring and tapped around it a few times. I also cleaned the area really good with brake cleaner and a small pick. After an hour test ride, so far so good, dry and no weepage.
