Persistent curses! vs wishing ring

[Genpin]

Let's say that you have a chiken on your head affecting your rolls, can you cancel it using a wishing ring or the only way to remove the curse is fullfilling the instructions on the card?

I remember reading in this forum that the only persistent curses (when they're already affecting a munchkin) that can be lifted by a wishing ring are the ones with no other "cancelling clauses" explained it in their text (like "big feet"), but, i cannot see to find the thread from wich i recall this...

Please help!