What happened when you attempt to turn the display with those belts? The ability to turn the feature depends on the torque of the motor and the ratio of the pulleys. If your sign is mounted on free turning bearings it should only have to provide enough torque to overcome the inertia of the feature. It should take minimal power to rotate it once it's moving. How much does the feature weigh, what type of bearings is it mounted on, what ratio are your pulleys, how much torque does your motor supply, how many RPMs does the motor turn at and how many RPMs would you like your feature to turn at?