If this is in reference to the original donut-style large adjustment system, typically, this is not a mechanical freeze-up of the parts, but rather a chemically induced freeze-up. Others may agree or disagree. This typically occurs when the scope has not been used for a long while and the original older grease within the adjustments system dries up and cakes-up and doesn't offer any more lubricant for the mechanics within the adjustments. It causes the adjustments to cease moving -- kind of acting like a soft glue inside the system. Before doing any of the below, ALWAYS make double sure the lenses are covered and protected properly. That stated, if you want to be patient and careful, you can carefully apply a small amount of either of the following via a needle dropper tube/bottle 1) some quality grease solvent to the moving edge of the rim of the adjustment rings and allow a few drops to soak in at several places around the adjustment rings. Be patient, as this may take a 2-4 days of multiple and careful applications in different areas around the edges of the adjustment ring. 2) Apply very small amounts of a super good quality penetrating oil (like Zero Friction by Pro-Shot) around the adjustment rings and allow it to penetrate and soak it. This make take two days. Once it penetrates well, the adjustments typically begin to free up to where you can turn them and feel the clicks again. And you should always wipe off any excess solvent or penetrating oil when you see it throughout either process. Parson's was good to me; but he was a bit slow; and you do have to chase for follow-up. There are others like Parson's that could service this issue for you if they are willing to take it on. Good luck. You have a small Jewell of optical history there.
