Hi! Yep, I know far, far more about photography than I've ever learned (or thought I learned) about reloading. Here's the "progress"...
The dies were left in the WD-40 solution for two hours, then I took them out and washed them off. I used a wire brush to clean the threads, etc. I loosened the lock nut on the locking ring, and it turned freely. I suppose I could have stopped there, but decided what the heck, why not take the three dies completely apart, and start at the beginning as if they were just new parts in the box.
I didn't get far - the small knurled knobs on the top of each die didn't want to turn. I figured that after 20 or so years, and a bit of rust, they were just "frozen" in place. So, I coated everything I thought was appropriate with penetrating oil.
Fast forward an hour - no change. Using pliers didn't help. So, I called RCBS, brought them up to date, and told them that my next attempt was going to be gripping the knurled nut in "vice grips", then use a large pair of "channel locks" to hold the die, and twist hard. RCBS said to go for it, and that they could always send me new parts if I damaged anything.
The "doing" was much easier than the "thinking". Channel locks on the die, and vice grips on the knurled ring, and just a little pressure, and it (they) all came off. So, I took everything apart.
The photo below shows what things look like right now. Some surface rust came right back, but I know how to get rid of that, and then oil the parts so there will no longer be any rust problem.
The first die (sizing, and de-capping) looks fine, just a bit of surface rust that I suspect will clean up fine.
The second die (for expanding the case mouth) should also clean up fine, but wow, it has all this "crud" on it. Maybe this is something that should be cleaned every year or so??? I have no idea. I'll assume it's fine (unless someone tells me otherwise), and clean and lubricate it.
The third die (for seating the bullet and crimping???), also looks fine.
I can explain all this to RCBS, and send them the photo, and see if they think I need anything new.
Note: all three dies looked pretty and shiny when they came out of the WD-40. They still look good in a normal photograph, but by using a flash, every speck of rust shows up, and they look far worse than what they would be if I just washed them off, and gave them a light coat of oil. I think I'll leave them in the WD-40 overnight, so there will be NO rust left whatever.