Autogyro pilot reported an aborted take off after main rotor components failed. The autogyro returned to the hangar for repair.

Narrative

I prepared for flight of a single-seat experimental homebuilt gyroplane in day; VMC; no wind conditions. Preflight inspection; engine start; warm-up; and taxi were normal. No other traffic was observed. After completing a preflight check; I taxied into takeoff position on the Runway and disengaged the rotor brake. With the control stick forward; I engaged the engine driven pre-rotator. Rotor system RPM increased appropriately. However; when I moved the control stick aft in preparation for takeoff; the control stick forces felt abnormal--increased movement of the stick with less pressure than usual. I confirmed pre-rotator was disengaged; cut engine power to idle; and moved the control stick forward. The rotor disc responded to forward movement of the stick but not in a normal fashion. The flight was aborted.Post-incident inspection revealed failure of the 'inner scissor plate' at the aft left corner of the mast. The broken part separated completely along a vertical line above and below one of two bolts attaching it to the mast. This part normally connects with two 'outer scissor plates' to which lower and upper push tubes are attached that control the rotor system. Failure of this part caused the rotor flight control system to be ineffective. Had there been any significant wind; I may have been unable to manage the rotor safely even while stationary on the ground. Had I not aborted; the aircraft probably would have tipped over during the takeoff roll. If the part had failed later; while in flight rather than on the ground; I would have been unable to control of the aircraft and the result likely would have been catastrophic. Had other traffic been waiting on the ground or approaching to land; I may have felt pressure to proceed rather than abort the takeoff. Although no crack or damage to the part was detected during the preflight inspection; electrical wires and a zip-tie securing them partially obscured the area from view. As a corrective measure; I will reroute the wires so that this area is not obscured from view during preflight inspection in the future. Also; the failed part was manufactured from 1/4' thick aluminum and will be replaced by a thicker part and/or one that is made from a different material less susceptible to vibration induced metal fatigue. I would also consider removal; inspection and/or replacement of this part on a periodic basis in the future.