Hello, I'm in Australia, I have an RXT-X 255, top speed was 113-117kph (70-73mph) @ 8140rpm by the Speedo, I recently got stuck on a sandbank, since then top speed has dropped to around 96kph (60mph) at the same revs, there also feels to be a surge or miss when pushing it hard, the wear ring was replaced last service & visually the prop looks fine & tight clearance to wear ring, is there something else I should be looking at? Any suggestions appreciated