Based on my many years of work experience at Yishan Compressor Company: 1. Foreign matter has entered the rotor, and the gap between the rotors is stuck, so that it cannot rotate. 2. The screw is displaced, mainly because the rotor is not rotated regularly. During overhaul and maintenance, the centering of the screw slowly shifted, resulting in unbalanced jamming. 3. The oil quality of the rotor decreased, and oil coking occurred, resulting in a large amount of coke between the screws, and the oil became increasingly viscous, leading to jamming< /p>