A bad wear ring will most only affect the hole shot....but a bad impeller and wear ring combo will affect both hole shot and top speed. I don't know what normal RPMs are for non supercharged engines, but 6000 seems about where it should be to go about 55mph.
TO rule out the learners key, what color is the Floaty Seadoo thingy on the lanyard? It should be yellow, white ones are learner keys.
Also, how do you know it has .2 hours? Mine only says the hour, no decimal places.
Matt