The Belimo FM24 Damper Actuator operates on either 50 or 60 Hz frequency and requires 24 VAC to function. With a power consumption of 6 Watts, this used product is designed for HVAC systems to control air flow in ducts. Belimo is a reputable brand known for producing high-quality HVAC damper actuators. This particular model, the FM24, is suitable for various HVAC and refrigeration applications in business, office, and industrial settings. The unit is not new and has not been tested so cannot vouch if functional. I have no circuit diagram but the pcb looks easy to fix, populated with a couple of analogue op amps still available.
eBay