One thing you have to take into consideration is the age of the crown. I've dug up 5 or 6 yr old crowns that were like trying to lift a 10 yr old oak tree. Just dig out about a foot or two from the center of the crown all the way around and you'll see what you have. You'll should see a bunch of rhizomes snaking out from the crown with little white buds on them. You can lop these off and use for additional plantings. As you dig down, if the crown is a vigorous variety, you may run into some pretty serious tap roots (think as big around as your wrist). If that's the case a spud bar is your friend. Don't worry about damaging the plant as if it's grown to that size it'll want to stick around for a while. Once you get it out of the ground you can trim it down to size and replant into a prepared area. Remember, when you buy rhizomes to grow new plants all you need is a little stick. You now have a great big crown with lots of carbohydrate reserves so it's gonna be pretty difficult to fail in this situation. Just make sure you have a couple beers handy! Have at it!