Agreed, you should try oiling it first..
Also even if the fan blade is fine, you may want to get anew one because it may be difficult to remove the exiting blade from the motor.
Be sure to keep track to the direction of spin of the motor CW or CCW , the direction of spin the blade is designed for, the pitch of the blade and the HP rating of the motor.
Also pay attention to the location of the blade how far on the shaft it is.
I'm a DYI guy and successfully replaced the blade and motor on my heat pump.
Just pay attention to the details.
Another detail is the routing of the wires, they must be securely attached so they don,t droop over time and get clipped by the blade.

Mark