Hello and welcome to Just answer,
Spray the area around the center hole and lugs with penetrating oil tap rotor lightly to "draw" in oil, allow oil to work a couple of minutes and strike the hub part of the rotor sharply with a hammer or "motivate" as you say, do not strike the friction surface unless you plan on replacing, if you are replacing the rotors yo can swing away here.
Let me know if you have more questions
Scott
ASE Master Tech/Instructor
20 yrs exp. Electrical; Driveabilty; Undercar; Airconditioning. Domestic and Foreign.