Sticking keys on keyboards, pianos, etc., any instrument with a mechanical leverage action, is not at all unusual. If the keys have a sloppy fit over the retaining bar and lots of space in between the keys, it takes more dirt, dust and crud to make them stick. If the keys have tighter tolerances, smaller amounts of particulate matter will make them hang up. Our local keyboard repair guy has related lots of horror stores about why the mechanics of these and other instruments fail. Sax players, clarinet players, trumpet players, and trombone players can all relate to sticking keys, valves, stems, etc., and most of these guys take care of their instruments as if they were an only child. It's not a Yamaha problem, it's just a problem associated with all mechanical devices.

Cheers,

Gary

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Travlin' Easy