Okay, I got my toolbars working on 2.4.1
I went to:
Site administration -> Advanced features -> Plugins -> Text editors -> TinyMCE HTML editor -> General Settings.
The editor toolbar field was blank. Even though a Default was specified, it was not working. So, I copied the lines of text from below "Default:" and "Each line contai..." and pasted them into the text field.
I repeated this for the "defaults" under available fonts list.
For me, the exact lines for "Editor toolbar" were:
fontselect,fontsizeselect,formatselect,|,undo,redo,|,search,replace,|,fullscreen
bold,italic,underline,strikethrough,sub,sup,|,justifyleft,justifycenter,justifyright,|,cleanup,removeformat,pastetext,pasteword,|,forecolor,backcolor,|,ltr,rtl
bullist,numlist,outdent,indent,|,link,unlink,|,image,nonbreaking,charmap,table,|,code
...and for the "Default fonts"...
Trebuchet=Trebuchet MS,Verdana,Arial,Helvetica,sans-serif;Arial=arial,helvetica,sans-serif;Courier New=courier new,courier,monospace;Georgia=georgia,times new roman,times,serif;Tahoma=tahoma,arial,helvetica,sans-serif;Times New Roman=times new roman,times,serif;Verdana=verdana,arial,helvetica,sans-serif;Impact=impact;Wingdings=wingdings