09 180 SE 255Hp impeller problems

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I have a brand new 09 SeaDoo Challanger 180 SE with the new 255Hp setup. When the dealer took it out to wet test they said it didn't want to go very good so they took it out and found a shipping strap in the impeller, so they took it out and said it would be good, I picked up the boat the next day and took it out on the lake, The very 1st time I hit the throttle the boat started cavitaiting really badly, I took it out of the water and checked it over at home later and found nothing visibly wrong. when taking it back to the dealer they said that the wear ring was shot and $300 later it was fixed and back on the water, and sure thing the very 1st time i took it out after being fixed the same thing happened and now they want another $300 to fix it , Has anybody else had this problem or have any idea as to what could be causing this?