(leaning out of the shadows for a moment..)
I've found that: removing the chord bars makes it -much- easier; only change one string at a time!! (I've heard of people unstringing the entire harp); change groups of 6-8 strings, then go back and return the previous group of 6-8. This helps keep the tension on the harp constant.
Then there's Maybelle Carter's opinion, "I'd rather throw the thing away and buy a new one" (somewhere on _Will_the_Circle_Be_Unbroken, too lazy to find it).