I am not familiar with the Neptune model sight glass, but I have always been able to get the glass separated from the gasket surface on all of my pumps with the use of a small wooden mallet. If it were me, I would put the ring back on and replace the bolts but leave them all loose enough for the ring to float freely and then I would deliver sharp blows from the 12 and 6 orientation and then the 3 and 9 as well. The ring just makes sure that when the glass does loosen, that it does squirt away and hit the floor. Spray on oven cleaner works well to clean up the sight glass, but be careful if the spinner has any painted surfaces. If not oven cleaner will handle the spinner as well. Neil