If it is the switch sometimes you can take them apart and clean the contacts and put them back together. Don't recommend it though.
If the motor just buy new one. Never be afraid to turn a wrench on your watercraft.:thumbsup:
Check your impellar for nicks and dings. If so change it. Go with a variable pitch impellar. Lower on the start higher on the top end. Solas. Go here and chose on. I recommend the X prop series. If you have specific questions call them. Solas impeller List
It could also be the wear ring but unlikely unless you sucked up a rock or something here is your parts site for your machine