I’ve followed that 37-video beginners’ tutorial in which we build a playground. I got to the point where there is a solid block sticking 4’ from the platform. I have drawn the steps with the Line tool and cannot see any gaps where the lines change direction.
I’m trying to use the Push/Pull tool to push out the steps. However, all I can select is the entire face and not just the part above the step lines.
You’ve got a couple of things going on, all related to the correct use of groups.
The ‘block’ itself is made of two groups, one the bottom and sides the other the top. This is no use in this case. The blue ‘bounding box’ is the giveaway that the geometry is grouped, if not grouped the face would show selected.
The edges you have drawn for the stairs are ‘Outside the context of the group’. Meaning you have not opened the group for editing before creating those edges and therefore they are not cutting the geometry of the ‘block’.
In this vid you can see that I am able to move the top away as a separate piece. I can then select and cut the edges to the clipboard, then open the group for editing and after drawing in an edge to heal the top I use paste in place to put the edges back. Then I’m able to push the geometry because everything is in the correct context. Note I have cut and paste in the context menu for display, you’ll have them in the edit menu or keyboard shortcuts.
You referred to a block you wanted to edit to make stair treads. If it was a group (or better, a component, you would need to “open it for editing” before your lines would interact with its geometry.