Yep, a linear actuator. Motor, pinion and worm gear driving the shaft in & out. Relays control motor direction. Limits could be torque switches internal to the actuator, hard to tell.
If lubing doesn't help you're going to be searching for some identifying marks on that actuator unit to try to find a direct replacement to keep from having to start from scratch on the drive. Or keep lifting to help the top "up", powering down....