You May Want to Save Your Time ...................
.............. and get it professionally repaired.
I had my Ritchie repaired a few years ago by a very knowledgeable company who explained the whole process of how the oil is replaced so there are no bubbles in it after years of service. Seems that after the oil is replaced in the globe, the whole assembly is then subjected to very high vacuum for 24 hours to remove any dissolved air in the oil. The globe is then sealed off. There is a diaphragm (which eventually leaks years down the road and causes the original problem all over again) which absorbs thermal expansion and contraction.