Abstract: A manipulation resistant combination lock is shown which has a housing, a drive shaft, a cam driver attached to the drive shaft, a bolt slidable into and out of the housing, a fence lever, a fence attached to the fence lever, and a set of tumbler wheels. A first end of the fence lever is pivotally attached to the bolt, and a second end of the fence lever has a dog which is engagable with a slot in the outer periphery of the cam driver. The cam driver is keyed to the drive shaft and holds two circumferentially spaced permanent magnets, one on each side of the slot. The dog portion of the fence lever also has a permanent magnet mounted thereon. The permanent magnets mounted on the cam driver and on the dog portion of the fence lever are arranged such that opposing magnetic poles generate a repulsive force as the fence lever approaches both sides of the slot in the cam driver.