Jeff's available for hire, but you probably can't afford him.

bitflipper
Turns out, it's not "Bruce" at all. What he's singing, in glorious stacked ELO fatness, is the German word "Gruss" (the correct spelling is impossible on a US keyboard). The original title of the song was indeed "Don't Bring Me Down, Bruce", but was changed because the song was to be premiered on tour in Australia. The name "Bruce" has an unusual connotation in Australia thanks to Monty Python, who had a popular comedy sketch at the time involving Australians, all of whom were named Bruce. The name came to be a generic word for "guy", like "Sheila" has become a generic synonym for "gal". Not wanting to offend any Australians, the lyric was changed to the even more obscure "Gruss", as in "Gruss Gott!", which I think is mainly a Bavarian expression. At least it seemed that way when I lived in Bavaria.

Maybe some Aussies and/or Münchners can elaborate on those connotations.

 
Just to weigh in as an Aussie, a Jeff Lynn fan, and a Monty Python fan, I remember listening to the song with my mates, none of whom were called Bruce. None of us could work out what "gruss" was supposed to be - it didn't appeear in the lyrics sheet, if I recall correctly - but it wouldn't have mattered if it had been "Bruce". Bruce may possibly have become a term for "guy" briefly in Australia because of Python but it's pretty unlikely; it was certainly only used in my circles in homage to Monty Python. "Bloke" is a better choice (such as, "he's a good bloke"). In any case, everyone I knew loved the original Python sketch, a version of which is performed here at the Hollywood Bowl (don't watch if colourful language or criticisms of American beer offends). This is the brilliant "Philosophers Song". Sounds to me like Jeff or the bean counters may have been taking things a bit too seriously there if the "Bruce" issue was really a concern.