An idler assembly is disclosed for a shovel having a flexible track assembly. In an embodiment, the idler assembly comprises an idler gear operatively associated with the track assembly; a sleeve; a shaft, sets of splines on the shaft and on the sleeve sized for engagement, and connectors at ends of the shaft; at least one bearing block forming a bore therethrough; at least one bushing liner disposed within at least one bearing block; and at least one retaining device for constraining the shaft from withdrawal from the bearing block. A method for retrofitting a shovel with an existing idler assembly is disclosed. In an embodiment, the method comprises positioning at least one bushing liner within a bore of at least one bearing block; attaching an idler shaft and an idler gear together; and positioning the idler shaft within the at least one bushing liner.