Mason & Hamlin sustain pedal:

[BDeTar@aol.com]

Garret,

I have run into many "squeaky" Mason Hamlin pedals that have ultimately
turned out ot be the damper lift tray hangers.  Try removing the action and
moving the pedal up and down several times while applying pressure to the
SIDE of the damper lift tray.  In other words, try to move the tray left and
right while engaging the pedal.  If your squeak disappears, you've PROBABLY
found the problem.  Try lubricating this bearing (McLube or ProTec "CLP" has
worked for me).

As an afterthought, there is a small leaf spring under the loud pedal that
can cause problems also.  It is possible for this spring to develop a small
crack which can cause a squeak.

I hope this helps!!

Brian De Tar,  RPT