The demand for precision in linear motion systems has led to increased efforts to minimize motion errors in linear guideways (LGWs). A significant source of these errors is ball passage vibration, caused by the recirculating nature of rolling elements (REs). Although gaps between REs may arise during operation and alter RE distribution, most studies of LGWs continue to adopt the simplifying no-gap assumption. Prior research has typically inferred RE distribution indirectly through vibration analysis, while the actual distribution under real operating conditions remains unclear, partly due to the lack of practical measurement methods. In this study, we developed a novel experimental approach using integrated inductive proximity sensors to directly measure the RE distribution in the contact zone of an LGW, and investigated the influence of varying loads and velocities on the RE Distribution. The results revealed that RE distribution is irregular and significantly affected by operating conditions, challenging the conventional no-gap assumption and providing new insight for LGW modeling and design.