Hi Andy,
What operating system are you using and what version of SketchUp. If it is Windows and SketchUp 2017 or 2018 got to Window > Extension Manager and check if it is there and enabled. If not it is not installed. If it is, then go to View > Toolbars and check CabWriter. If it is not, write me at jpz@srww.com.
Joe…..