Miner had just completed adding oil to the Hitachi ZX450 excavator when EE stepped down onto the track. After stepping down onto the track. Then, slipped on the track, fell against the catwalk of the machine. EE completed EE's entire shift. It was not until the end of shift EE noted pain in EE's rib area. EE did not report the accident until the following morning (5/6/2022).