This paper presents a case study investigating the impact of a machining error in the shaft of a medium-sized Vibrating Screen on its operation and vibration parameters. In vibratory equipment, the operational principle relies on a mechanism comprising a shaft with eccentric masses at each end. Depending on the machine's purpose, one to three drive shafts may be present. Precision manufacturing is crucial to ensure minimal positional difference in the center of gravity between the eccentric masses at both ends of the shaft. Even a slight error in manufacturing these eccentric masses or premature wear in the key and shaft can result in distortions in the vibratory movement of the machine, leading to potential structural failures such as cracks and component fractures. Apart from structural issues, such defects can result in performance loss, causing substantial losses for large-scale equipment. This study delves into a detailed analysis of a machining error in a drive shaft that resulted in distortions in the vibratory motion of a Vibrating Dewatering Screen, model AI PVD 4818 1A, with a nominal length of 4.8 m, internal width of 1.8 m, and a total weight of 66267 N. The manufacturing error in the shaft resulted in such significant distortions in the screen’s working motion that it completely hindered acceptable equipment performance, necessitating the replacement of the faulty part.