I have a Yamaha P-115 that has recently developed an odd issue. Yamaha tech support didn't really have an ideas. When I turn it on 4 keys are dead. These are the two highest C#s and the two highest Gs. 4 keys, same keys in two different octaves. Typically if I just play for while they start to work again, even if I haven't touched them. Tech support suggested the contacts were going bad. Perhaps, but the pattern seem odd. If contacts on 4 random keys are going bad, why would it be the same two notes in two different octaves? And why would it spontaneously repair over time without any of them being touched? I live out of the US, in an area where there is no technician. Nor am I terribly mechanical so the idea of diving into this keyboard with a screwdriver in hand is a bit daunting. Beside, it smacks of an electronic or software problem to me, rather than a mechanical one. Has anyone ever heard of something like this? Thanks for any ideas.