I just bought a 1999 SLTH used from a friend. It has sat for 7 years but worked before parking it. I have sprayed it down and everything looks good. I removed the plugs and shot some pb blaster in there to do it's work. I inspected the fuel lines and all look fine but I will be replacing all of them. I picked up new plugs and a battery. I ordered a carb rebuild kit to do as well. This week I was planning on pumping the oil and fuel out and replacing with new to see if she even fires. After this I am trying to figure out how much work I should do and what might be excessive. I am very mechanically inclined yet I have not worked on a jet ski myself but have automotive for years. I guess my questions are should I do a complete rebuild on the engine, just replace all the gaskets or leave it as is if it fires up ok? Also I was planning on rebuilding the jet assembly just because I know he never has. I appreciate any tips and advice as I am no expert on these but I want to do what I can do things right. I also saw the pre-mix mod and not sure if I should do this now or not. I don't know if it is something i really want to do or not.