<html> <body> Hi Bill, <blockquote type=cite class=cite cite="">I was just worried about two issues (but probably don't need to be). 1.) the change in leverage from the old to new underlever. That amounts to the new underlever being lifted a couple of .1mm higher (eyeballing it) for the same key end lift (which will increase because that shank knuckle distance is going from 16 to 17mm). </blockquote> Replacing the key end lifter felt can take care of this, it also makes regulating the dampers easier with no fudge factor. If you want the lifter felt thinner, iron it with a damp cloth as in pressing a pair of pants. You can steal a good 1-2 mm that way. <blockquote type=cite class=cite cite="">So I'd have to raise the sosty rail a sheep hair. 2.) the '73 damper levers have return spring through #28, where the new have none for what (I'm guessing) is the same leading. Should I worry that #1-28 are now only being held to the string by their own weight, with no springs? </blockquote> I would not worry about the springs, but I do have a tip for you.  Put a dab of CA glue around each underlever lead. I have noticed quite a bit of what I call "smear noise" coming from damper leads. It is noticeable on many 10yr old plus pianos.  This is also true for key leads. Regards Roger </body> </html>