I dont know. I have seen a couple of them. However they were sealed all those many years ago, they obviously were no longer sealed.As used by the USMC in WW II, how well were they sealed? I don't think nitrogen filling was a thing at the time.
Fun fact, when bases are mounted at the correct 7.2" center to center spacing the amount the click moves the scope for 1/4" at 100 yards is .0005".
.Parsons scope service used to do a wonderful job on Unertls. I dont know if they are still in business