Have 2 - a 2001 XP & 2000 RX. Super powerful & reliable... just be sure anyone using it understands that, if they dunk it, to stay calm and remember to roll it over IN THE PROPER DIRECTION. If they don't, you'll be paying for $$ rebuilds [just ask my son]!
Agree w/compression test as that's the tell-tale. Strongly recommend water testing as well. [In fact, get it properly warmed-up and run it for at least 15 minutes and its performance should alert you to any problems.]