Mr.fixit,
May I ask WHICH ball you no longer have in the tray?
If you do not have the "i" ball, right click on the "a" ball and see if you have "Merge into Avast icon" checked.
If so, uncheck it. Avast can merge the two icons into one to clear up the tray.
IF the "a" icon is missing, then try to activate Avast from the Start menu folder.
If you know how, open up the Start.ini file using the MSCONFIG utility. Do you see the file Ashdisp.exe?
Lastly, let me know what OS you are using so I can clearly explain any necessary steps.
Thank you for asking for our help,
techie