This has been covered a few times here, but i for one don't mind repeating. The instructions apply to a like new bike. Unfortunately the fork tubes above the lower clamp, hidden behind the headlight ears, are not plated and in a few years, let alone 30+ years, they grow barnacles like the hull of a ship. Rust and corrosion, they will NEVER slide out like the instructions say. You will need to slide a lever, i use a tire iron, into the bottom clamp and lever it open while tapping down, and it may be a hard "tap" on the fork nuts. Twist the tubes, and shout and curse and they will come out.
Once out you can clean them so they won't be so hard going back in.
Don't forget to loosen the fork cap nut while it is still clamped in the bike, much easier now than later. Leave it snug, just break it loose.
