1. The first thought should be "Tiny Cooling Fan" motor lubrication is not, leading to drag after a fan mounted on the motor can not. You remove the fan, plug in the power, if the shaft can rotate, indicating that this problem, if not that is the other problem.
2. Your fan is not overheating, motor overheating can cause deterioration of the motor with a load capacity, low active power of the motor, making it impossible to drive the load.
3. Next, you have to consider the "Tiny Cooling Fan" with how long, the motor loss, after the motor bushings wear, it is easy to burn. Motor with a long time, it will also make the motor resistance increases with load capacity becomes low, making it impossible to drive the blades rotate.
4. Another is "Tiny Cooling Fan" start capacitance becomes smaller, although the nameplate reads those parameters, but a long time, the capacitance is reduced, leading to reduced starting torque of the motor, can not drive the load. This simple, remove the capacitors, go for a new model of the same should be no problem. But the best for a 20% larger than the original, you will get better results.