[CH]

I have a 1938 Progress made PEM scope that has some moisture behind the outermost ocular lens. I thought to detach the lens in order to clean it but after releasing the outer locking ring it still seems something is holding the lens. Any ideas? TIA

 

[Mosinmeister]

I don't know what they would have used in those days but I would guess they used some type of gum mastic or gum arabic to seal the lens in place. It may have dried up and cracked over the years allowing moisture to seep behind the lens as you describe. Can the rear lens housing be unscrewed the lens accessed from the inside? Just my thoughts on it.

 

[Vic]

Its just crud Antii. Try tapping it on the table face down.

 

[CH]

Thanks, tapping was the key. I'm not sure what the crud actually is but my best guess would be beeswax. The structure of the eye-piece is very simple. Behind the outer biconvex lens there's just a short steel bushing and a bonded doublet lens. Pretty much like this SVT scope: