Stuph in Yamahas

[Ron Nossaman]

Hi Gang,
I service three Yamaha grands that have what looks for all the world like a
blotch of graphite powder on the inside of the case. In all cases (sorry),
it's on the bass side, about two inches down from the rim top to the center
of the splat, between the hinges, and at a point roughly below where the
lid locator pin would be if the piano was on it's side. So far, since if I
tried to wipe it off and left an indelible mess it would be my fault, I've
taken the time honored cowards' approach of pretending it's not there at
all. To this point, the technique is working, but something tells me this
grace period can't last forever, and someone is eventually going to notice
the stuff and want it removed. This coincidentally brings me to my
questions, and the reason for the post. See? Sometimes I really do have
reasons for what I post, despite alleged evidence to the contrary. Has
anyone else run into this, what is the stuff, how did it get there, and how
might it best be removed without undue trauma, angst, pathos, and
accountability? 

Awaiting enlightenment, 
Ron N