Hi,
I had a large motor once that had the centrifugal start mechanism stuck. It was stuck in 'start' mode all the time so the motor would never come up to full speed. What worked was to disconnect the start mechanism switch and replace it with a push button switch. The button became the "push to start" switch. To start the motor you would push the button and hold it in for about 3 seconds, then once the motor started turning you would release the switch and it would come up to full speed. So that's one way to do it. A little more trouble to start but not much as it was a motor used with a human operated device anyway not an automatic device so it didnt have to start by itself.