FYI some of the vintage sets the stickers become brittle over time; any attempt to peel the sticker off in one piece can sometimes result in the sticker breaking and tearing off.
I experienced this when trying to re-position the side hull sticker trim on an old 3750. Newer playmobil stickers seemed to come off in one piece easily, and were easily re-applied. I took this for granted and didn't realize the older stickers would be a bit more fragile. I imagine a vintage schooner sticker might suffer the same fate.
My suggestion would be to take a hair dryer on low setting, and slightly warm up the plastic and the sticker. it might help revive the old sticker glue that has since gone completely dry and brittle, causing the sticker to stay stuck to the plastic. Heating it may make it more workable and less prone to break. But if it's already old and going to break anyway, there may be no stopping it. Just baby it as much as possible, little by little, as you peel it slowly.
