First question is; When the fan is off, is it hard to turn the blades, if so try this first:
The solution that worked best for me this year was to open the top cover that the fan/motor is attached to, turn it over so the fan is upside down with the shaft pointing up and oil the shaft with a turbine grade oil. I purchased a Zoom Spout Oiler by Supco (you can find it @ many places online) and it has worked great. The key is to get the oil down the shaft to oil the bearings. After oiling it, give it several spins in both directions and add more oil while let the fan sit upside down for 20-30 min or so. The fan should loosen up considerably and should start on it's own. If it loosens up and doesn't start maybe try a new capacitor.
Let us know how it work out. Good Luck!