Hi, I once had a customer with an inexpensive probably Chinese made grand 3 years after it was built the keys were binding. I could not reach the manufacturer of it but contacted a technician the US plant that probably contracted its construction. This swelling key led problem can be seen rarely and I have seen it in older pianos. Because the oxidation is a yellowish powder I wonder if it is zinc? Anyway this 3 year old piano probably built in 1997 keys were binding all over it didn't seem to affect the dampers. The top surface of the keys had been finished I don't think this is relevant. I took each key and with a sharp chisel or safety razor sliced off the protruding lead. Wear gloves don't make dust and store the leads. Then I shellacked the surface of the lead. This was done in 2000. I saw the piano last about a year ago and everything is still okay. I was unsure how long things would be okay. Jessica Masse RPT
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