Yamaha waverunner starter or relay?

I have a first generation waverunner wr500. It runs great but has an intermittent problem starting. After riding a few hours(continuously cutting on and off) it will not turn over. press the button and nothing happens. No clicking, nothing. After sitting for about 30 mins or so, it will start right up and ride for a couple more hours. Does this sound like a starter problem, solenoid problem or something else? It seems to happen and random intervals and start working again with no action but letting it sit. Anyone else have any similar problems.