The cmi rs500 has four steering modes front /rear /crab and articulate so yes it can crab walk The steering can be easily calibrated and all eight sensors are identical for ease of spare parts [ one on three of the four legs for height as two r/h legs are tied as one /one on each leg for steering and one on the steering wheel under the dash} if nobody has been adjusting the calibration prior to the problem i would be checking the small flex drive coupling between the leg sensor and drive pin as it may have failed or loose on the shaft