Do you have to reintroduce new worms after you empty the compost?
When you empty your castings and compost, the worms will not be with the castings, but where the food is, on the other side of the Subpod divider.
When the system is getting full, stop feeding one side. After two weeks, most of the worms will move to the other side where the food has been added. This allows for easy harvest of the castings from the unfed side.