The motor always starts in high speed no matter what speed is selected. Once the motor comes up to speed, the centrifugal mechanism in the motor activates the motor switch and the motor will go to a lower speed if one has been selected, otherwise it stays in high speed. Normally, this switching of speeds takes place very quickly and is not noticeable. If it's taking a long time to switch, the motor centrifugal mechanism may be sticking or the motor switch contacts may be sticking. You can take the cover off the switch to examine the contacts. Another possibility is a weak starting capacitor which is used to provide the starting torque necessary to get the motor going.

Eric