<html> Tom, I like Wim's explanation - it sure sounds like there is lost motion, which in this piano could be allowing the keys to look out of level. Once in a while older balance rail punchings will do this also, as your leveling job spun them randomly.  As they are used now after your regulation job, the punchings which have non-compressed spots positioned so that the keys were sitting on them have become compressed by the use. New balance rail punchings would be the answer.  Use thin bushing cloth type, and iron them before installation. The fireplace is the most likely reason for the tuning changes.  This has been a bad winter for tuning stability, as the northern US was so warm in December, then turned cold recently making tunings go sour all over. Don Mannino RPT </html>