When you "Jump the solenoid" on a seadoo... you won't hear a click. You should be using a heavy set of pliers, and jump across the cable contacts. If you do that... you will be sending power right to the starter. BUT... that doesn't necessarily mean your starter is bad. Your cables could be corroded, and yo won't get enough power to the starter to spin it.
The best thing to do is to remove the starter, and check it directly.