"I have just received a request from a missionary in Sudan, for a piece of music wire to replace a string on a Yamaha M1J. B4 is the note." Bill, This piano (M1J) was never sold here, but all the M1 scales, save one, use a size 17.5 for note 39. The one that doesn't is size 18. Be safe, send both. Mark Wisner .
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