Horizontal movement of SustainPedal

[Michael J Millett]

\version "2.8.4"
Mac 10.39

I am trying without success to move the sustain pedal marking 
horizontally. Shouldn't this be doing it?

\once\override SustainPedal #'extra-offset = #'(-3.0 . 0.0)

or

\once\override Staff.SustainPedal #'extra-offset = #'(-3.0 . 0.0)

I see reference to this working: \override Staff.PianoPedalBracket 
#'extra-offset = #'(2 . -2),
but I am not getting it to work. I'm trying to move the symbol, not the 
bracket, anyway.

I've also tried without success:

\override SustainPedalLineSpanner #'padding = 1

and

\once \override Staff.SustainPedal #'self-alignment-X = 1

Thanks for your help,
Michael