<div>The possibility of seasonal shift, coupled with a move(change in environment)or new air conditioning/heating (duct blowing directly on the piano or a portion of it)coupled with a move and a third possibility added to the mix  the owner or someone playing the same piece with a heavy hand over and over. Here's where previous tuner error or when was it last done enters the picture. A solid tuning, one that has been pounded in by a reputable technician will stand up to that sort of playing and not go that far out of tune. I have found some of the tech's in my own area do not pound in their tunings and the tunings tend to "drift" rather quickly. </div> <div> </div> <div>One more nugget of info I have been tuning for a Kawai dealer for over 20 years, about a 15 or so years ago Kawai began getting complaints about string tarnishing, they'd turn black or dark rather quickly. Then it stopped but I noticed a change in the way they tuned. If a pitch raise of anything approaching 25 cents was necessary I noticed the phenomonen of the strings slipping around the hitchpin! I came to believe the strings were being coated with something to froestall the tarnishing and it was slippery enough to cause this problem. I modified my tuning method to compensate. I tune two notes at a time(center string) then the RH string of the upper note and the LH string of the lower note then I remove the center mute and tune the LH of the upper and the RH of the lower. In this fasion I am immediatly tuning the "other half" of the center string before it has time to slip around and the same with the RH lower/LH upper. </div> <div>I don't recall the 502's and the exact age of them but I'm thinking they might fall into this time frame, check the manufacture date. The time I'm thinking of was late 80's into the early 90's  </div> <div> </div> <div><br><br> </div> <div><span class="gmail_quote"></span> <blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid"> <div style="FONT-SIZE: x-small; COLOR: black; FONT-FAMILY: Arial; BACKGROUND-COLOR: transparent"> <div> </div></div></blockquote></div><br><br clear="all"><br>-- <br>Michael Magness<br>Magness Piano Service<br>608-786-4404<br><a onclick="return top.js.OpenExtLink(window,event,this)" href="http://www.ifixpianos.com/" target="_blank"> www.IFixPianos.com</a><br>email <a onclick="return top.js.OpenExtLink(window,event,this)" href="mailto:mike@ifixpianos.com" target="_blank">mike@ifixpianos.com</a>