On June 27, 2001, at 1010 Pacific daylight time, a Beech A36, N808NH, experienced restricted elevator control movement while performing a go-around at Meadows Field, Bakersfield, California. International Flight Training Academy was operating the airplane under the provisions of 14 CFR Part 91. The certified flight instructor (CFI), dual student, and two passengers were not injured. The local instructional flight departed Bakersfield at 0921. Visual meteorological conditions prevailed, and no flight plan had been filed. According to the CFI, during the incident flight the student was performing an approach to Meadows Field when air traffic control tower personnel instructed the airplane pilot to go around. Due to the student's delayed response, the CFI stated that he assumed control of the airplane and initiated the go-around. While reconfiguring the airplane, the nose came up too high, and holding forward pressure on the control wheel and pitch trim reduction seemed ineffective. The CFI indicated that he applied additional force to the elevator control, the controls freed, and the nose abruptly pitched down and became jammed in a nose low attitude. The CFI again pulled back with great force, the elevator control freed, and the nose came up to an excessively nose-up pitch attitude. The oscillation continued for about three to four cycles. Roll and yaw controls were not affected. The CFI indicated that he successfully maintained control of the airplane and landed in a flaps up configuration. A post-incident inspection of the airplane revealed no pitch trim abnormalities. However, the elevator exhibited evidence of mechanical binding. A more detailed inspection revealed that a screwdriver had been left under the airplane's floor in proximity to control cables. Specifically, a 10-inch-long screwdriver was found wedged between the nose gear actuator retract rod and the elevator control cables beneath the forward spar cover, between and under the pilots' seats. As the nose gear retracted, the nose gear actuator retract rod moved the screwdriver against the elevator control cable resulting in binding. When the screwdriver was removed, the elevator operation was normal. A record review revealed that on June 25, 2001, a contract mechanic had performed maintenance on the airplane. The maintenance required taking off the forward spar cover to allow removal and installation of a flap motor gearbox assembly and flap flex drives. Since this maintenance, the airplane had been operated 5.8 flight hours.