Hi and thank you for your question.
The short answer is, especially on the tune up, no, it isn't difficult at all. Being an electronic ignition, about all you can do with regards ***** ***** maintenance (tune up) is replace the spark plugs. Since its a 2 stroke there is no engine oil or filter to change, no points, rotor, cap or condenser.
The carbs aren't too bad to work on either. There are a few more parts involved but not overly complicated.
NOW, the disclaimer. If you need anything other than spark plugs or carb parts, you probably arent going to be able to find it. Soooooo, if it is turning over now with the electric starter, I would check for spark on all 3 cylinders and compression on all 3 cylinders. If you are missing either one on any of the 3 cylinders then spark plugs and carb rebuild is the least of your worries. The point being, lets make sure that is all it needs before we take the time and spend the money replacing the spark plugs and rebuilding the carbs only to find the engine has no compression or no spark. Since Polaris got out of the water craft business shortly after 2006, parts availability is getting pretty scarce.
If you have any more questions, feel free to ask.