Pianotech

Greetings --

Steinway D, 1983. New action parts and strings about 10 years ago. Over the last week or so the D5, first note above the treble action break, started sounding muffled. The rest of the piano sounds fine. I found that spacing was a little too far to the left relative to the D#5 above it, and the right string had made the hammer shape a bit lopsided as a result. I recentered the hammer, filed it down a bit so it was once again flat and square with the strings, and this helped a lot. But it still sounds slightly muffled in relation to the notes on either side. Touched up voicing of the surrounding notes and got another good improvement, but it still needs a tiny bit more. Today's question: How can I brighten up that one note, D5, just a little bit, so that it once again fits in but doesn't over power it's neighbors?

-- Thanks