Cannot end extrusion along the z axis? I was extruding on the z axis, then attempted to extrude along the x axis. I tried to right click to cancel the z axis extrusion (unsuccessfully). Then right clicked again, to newly select the faces on the x axis to extrude (unsuccessfully). The two arrows, (x,y front view) remained were they were.  I can change the axis constraint, but I can't extrude from a new location and would like to.
Thank you for any help you can offer!
To cancel an axis constraint, such as the Z axis, hit the same axis key two more times and that will remove the constraint. You can then hit another axis key for another constraint.