If you have access to a vibratory cleaner, such as a jewelry cleaner, just drop the entire die into the holder with standard jewelry cleaner and let it run. Go to bed, wake up with the case hanging out! Easy as pie!
Other wise, the Easy-out should work as long as you don't touch the sides of the die wall. Use lots of Kroil or other penetrating oil. Even WD-40 will help. The vibratory cleaner is the easiest and has fewer headaches unless your wife catches you using her jewelry cleaner!
If worst comes to worst, you can return it to RCBS and they will either remove the case or send you a new die. They will do this for free and no purchase receipt is required. RCBS is a good company with excellent customer service!
If you have a size die that is scratching cases, first clean the die out with Flitz or some other metal cleaner (JB non-embedding cleaner, stainless polish - available from aircraft supply houses since it works on aluminum, too, etc). Use a nylon brush and cloth patch & hook the brush up to a drill motor. Don't let the die get hot, if you do, you're overdoing it! If that doesn't work, return the die to RCBS and they will polish it out for free! I usually have several size dies for each caliber (over 50 years of collecting them!) And when I get enough to fill a die set box, I just send them back to RCBS for care all at the same time! This repair/replace also holds true if you're one of those guys that like to use your inertia bullet puller like a framing hammer... they will replace those for free as well. Personally, since I found out how they are actually supposed to be used, I've had the same one for over 30 years now and have pulled lots and lots of bullets with it without breaking it! It's all in the wrist, which is all you should use!
Cheers,
crkckr