In an aircraft with tab-flown control surfaces, how can a jammed surface be detected during preflight examinations or flight control checks?
The system you describe was used on large aircraft before hydraulic actuation became standard. The proper name is servo or Flettner tab.

The preflight check would ideally have one mechanic move the cockpit controls and a second mechanic walk around the aircraft and command control movements. While the actual control surface would not move, the servo tab would, and the second mechanic would hold on to the tab to check if it does so against moderate resistance. Then he would manually move the control surface to check if it moves freely through the full deflection range. This might require climbing on a ladder for the second mechanic, but would be the only way to ensure proper function of the control system.

One pilot by himself would not be able to properly check the airplane.