Changing the stator requires removal of the flywheel, in the magneto housing! A three way pulled will be needed to get the fly wheel off, and the engine will need to be out of the ski.
If you need a stator for the 720 I have one for sale PM me
depends on the engine. on the 951 it's not that hard, but on a GTX (with a 951) you'll have to remove the pipe... on my XP i was able to swap mine (twice) without removing the pipe (first time missed a piece that ran the oil pump!)