Identify the root cause of 'ring walking' in a shaft-mounted spiral retaining ring application.

'Ring walking' is a phenomenon where the retaining ring slowly rotates and eventually moves out of its groove. This is usually caused by 'precession' due to a combination of vibration and a loose fit between the ring and the groove. If the ring's free diameter is not small enough to provide sufficient 'cling' on the shaft, or if the groove is oversized, the ring can vibrate. Under cyclical axial or radial loads, the ring may rotate slightly each cycle. Over time, this can wear the groove edges or the ring itself. Troubleshooting involves checking the 'cling' (interference fit) of the ring and ensuring the groove width $W$ is within the specified tolerance (typically $0.003$ to $0.005$ inches wider than the ring thickness $T$).