Changing the state manually is an intuitive way to look at this, but it doesn't work quite the same way. This is because if an operator is in the middle of a task sequence when he goes down, the manual state change will immediately be overwritten by the task it's performing. What you can do is add a delay task sequence for the duration of the breakdown time. We did this by changing the down and resume functions from "Stop Input" and "Resume Input", respectively, to "Travel to Location, Delay Until Down Time Complete" and "Do Nothing". Then in the code for the down function, you can remove the travel task sequence, and for both of them make sure to still set the label values for "opAvail". Then in the State Bar chart properties->Utilization Analysis make sure to include "scheduled down" in the chart. See updated model.