I'm glad you asked, because I'm in the middle of my first underlever system replacement, and have similar questions. I'm taking a horrific loss in terms of the time spent thinking about this as I do the work, but hope to only have to over-think on the first one. So I want to learn about all the possible variants, even the ones that don't apply to this first job - sooner or later I bet I'll see them. In addition to the Renner instructions, I've been referring to the Journal article by Tim Dixon RPT (August and September 2001). His recommendation is to locate the pivot pin hole further forward in the tray so as to locate the tip of the sost. tab in the same place as the original. Although this might incline the damper wires off of vertical, he doesn't consider this to be a problem. Tim also recommends setting the horizontal (front-back) location of the new tray off of the top post center pin, rather than the tip of the underlever. This was key to my job, this time, because the center pin to underlever tip distance on the originals was 3mm longer than on the replacements. If I had put the underlever tips in the same location, that would have moved the sost. tabs 3mm closer to the action. After y'all have chimed in on David's specific question, I'd like to hear about all the other dimensional discrepancies you've run into, and how to deal with them. thanks Mike David wrote: Frequently when installing new Renner underlevers I run into the problem that the new sostenuto tabs extend farther out than the old ones. Moving the sostenuto rod in far enough to allow for proper regulation often results in clearance problems between the backchecks and the sostenuto rod itself. What is the best way to modify the original set up such that I don't create other problems. David Love davidlovepianos at comcast.net <https://www.moypiano.com/resources/#archives> www.davidlovepianos.com
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