Hi everyone, I hope this is the right place to ask this question. I'm looking at buying a 1971 Yamaha YC-30, it is pristine and all original, however, the seller says that "The second F# of the white keys is constantly 'note on' on the 8' level. It is fine on all other levers." I was wondering if anyone knew what that problem may be, and if it might be a difficult fix for me to do myself. I'm decently handy and I know how to solder and wire things, so I'd be happy to replace a diode or a capacitor myself, but I'm just a bit wary that at it's age the problem might be something which is a bit more substantial than just a diode and might be quite expensive, out of my abilities and, possibly not worth the purchase. Thanks in advance!:)