A yamaha dealer will be your best bet,pretty expensive mind you,and very hard to seal a corroded starter back together to last for long. I have mint fresh water starters available (no corrosion),shipped anywhere in NZ for $200. Stripped down,lubed and checked and reassembled with new seals. Bench tested. Good to go....
http://jetskijunk.co.nz/en/765-psykho-s ... 50701.html Like under $180 with discount and after selling for two years we have had one back ever. Not bad value for new.
Found the brushes at motorcycle shop not oem but at least the rest of the starter is! from what I've herd oem is the only way to go cheers anyway guys