I will do that TIG. I didn't do it after I made the correction, because the plugin wasn't mine and Jim over the years has made me a couple of life-saving plugins.
I am not a code writer. I am sure others will find this not the optional solution, however, it does work for me. I would like to see this plugin modified so it is correct for 2019 and future versions of Sketchup but don't wish to step on anyone's toes.
See the attached PDF document to see how I modified the directory "Toolbars" to make the plugin work.
The short answer is I moved the plugin "Loader.rb" from the directory "Files" to the directory "Toolbars"
The structure of the 2018 toolbar directory.pdf