B747 pilot reported the elevator control was not functioning properly during pre-flight checks and there were multiple log book entries documenting previous elevator malfunctions.

Narrative

I arrived on the aircraft to find maintenance reviewing a repetitive inspection on the autopilot. I asked if there were more than one written up due to the overhead circuit breaker panel showing more the Left autopilot servo circuit breaker pulled and secured along with the Center autopilot servo. It seemed a bit strange to have 2 autopilot systems inoperative at the same time so I started to review the previous discrepancies in the logbook. Log page X on Day 0 shows Right elevator outboard No deflection written up item 1. Replaced and adjusted as well as signed off under AMM XX-XX-XX. What I find unusual is item 3 on the same page; Adjust elevator body cables. Then on log page Y on Day 3 When doing the flight control check; at 3/4 nose down the yoke get stiff; then you must give extra force for full down deflection. Item 2 shows #1 AFDS (Autopilot and Flight Director System) servo ground test fail for 'Elevator Servo-L Fail'. The Left Auto pilot is deferred on log page Z item 2. Then on Day 4 log page A item 1; the flight control check for elevators is written up again for a second time. The discrepancy is cleared by performing cleaning and lubricating of elevator fwd quadrant and adjacent cables and pulleys. On Day 5 log page B item 1; 'the Center Auto did not function' was written up. After seeing these several alarming coincidences; I contacted dispatch and told them to patch me in with maintenance control and the duty pilot. I told them after reviewing the log book; that I felt uncomfortable in flying the aircraft until these issues are completely investigated and repaired. The duty pilot asked me if I would perform a control check on the elevators. I performed a control check and found the elevator control became very stiff at 80% nose down. A significant amount of force was needed to move the elevators completely full down. Also; when pulling the nose up; about 50% travel up the control became stiff and more force was needed to get full travel up. Discrepancy was entered into logbook. A report was filed. I am not sure if all these events are related to each other but there are too many coincidences for me to believe the aircraft can be operated safely. I think the control checks were being either rushed or too aggressively done to noticed the problem. After the flight was to resume the next day; I was informed by a source in maintenance that a control rod was found broken and 2 others were out of adjustment. The flight did not commence as scheduled and was further delayed for maintenance. Proper control checks done slowly and smoothly should reveal any potential problems. There should be no binding or extra use of force throughout the travel of the control yolk. A further look at the beginning of how the sequence of events needs to be addressed from a maintenance perspective. Did the Aircraft Maintenance Manual have a flaw in the procedure relating to the elevator position problem being addressed? Why were the elevator body cables adjusted and was that procedure correctly followed.The seriousness of broken parts within the elevator control system should not be taken lightly.