I've owned a 10X and a 20X Lyman All-American Perma Center scope and was impressed with their optical quality. Both showed no sign of internal fogging, which leads me to believe they were purged. They obviously don't have the lens coatings that todays optics have, so the low light performance won't be as good. The adjustable objective allows you to correct parallax error for given distances and is a nice feature.

If your scope is in otherwise excellent condition, I'd have it repaired. You can't touch something like that for $100 today and it's much better than the Korean or Chinese scopes in the $100 price range. I think you'll find that vintage scope dealers are selling the fixed power Lyman All-Americans with an AO for upward of $300.

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