Mason & Hamlin sustain pedal:

[Newton Hunt]

      One of the best things that can be done is cleanliness is next to
noiselessness.  Too much lubrication is as bad as too little.
      Before a problem can be solved its source has to be isolated.  There
are several friction points in the pedal system and each one must be isolated
and eliminated as source before trying a fix.  Shotgun type solutions rarely
work well.
      Customer shoes
      pedal pivot
      lyre mounts and braces
      Lyre slot linings
      Pedal rod bushings pedal end
      Pedal rod bushings guide rail
      Pedal lever pivots, linings, blocks
      Pedal spring, spring friction point
      Pedal pitman, linings and contact points
      Damper tray pivots, blocks and felts,
      Damper tray spring, retainers
      Damper wires and guide bushings
      Damper lever leads, bushings and spring seats.

      Those are for only the damper or sustain pedal.  The others have a
similarly long list of places to check.  Check each, clean as needed and use
an appropriate lubricant for each point (mostly VJ lube from Pianotek) and if
the problem persists let me know.
            Newton J. Hunt
            nhunt@gandalf.rutgers.edu