<HTML>In a message dated 2/21/01 5:46:09 AM Central Standard Time, dnereson@dimensional.com writes: <BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">Set the temperament, tuned octaves to the top, then started in on the bass, and while tuning bass unisons, I heard "the big bang".  Now the first octave of the plain wire section was suddenly a quarter-step flat, but the bass and rest of the treble were still up to A=440 level.  So I took the action out and with a bright light inspected the plate very closely and could find no cracks.  There was one hitch pin that had two very small hairline cracks around it, but someone (maybe the factory?) had relocated the hitch pin about 2 inches lower, out of the cracked area.  I searched and searched and could find no evidence of plate cracking, rib separation, bridge splitting, pinblock separation or anything else having given way</BLOCKQUOTE> I heard that once, and the soundboard cracked. Perhaps there is no rib separation, but the crack could still be there somewhere. The customer heard it, and called me back later to complain about a "funny" sound. I told her the soundboard cracked,     and that there was nothing I could do about it.   This is one of the reasons I never raise pitch an old upright. It happened to me once, I don't want to have it happen again. Willem </HTML>