Hi Robert,
It seems that the fastest way to search for such characters is to use Filter/Profile column values dialog from column’s right click menu. Suggestions tab of that dialog will show you a message if the selected column contains system characters:
Filter button in that message will create a “Filter by condition” transformation which will show you all the cells with hidden system characters.
There is no need to open that dialog for each column - you can switch to a different column by selecting it in a dropdown list at the top of the dialog or by clicking on the column’s header.
By the way, if you’ll need to just remove system characters from the whole table, you can do that with “Sanitize text” action configured like this:
