Ball screws and linear guides are among the key components of machine tools. Abrasive wear causes a loss in stiffness of these components over time affecting the attainable manufacturing precision and, eventually, leads to failures and costly down-time. In order to control these effects, the condition of the crucial feed drive components needs to be monitored. This paper shows, how the feed drive condition can be monitored by looking at the modal parameters of the system. It will be shown, that preload loss cannot only be detected globally, but can be traced back to the worn component. A distinct test cycle was developed for this purpose.