Zuki,
Call Yamaha's customer service department at 714-522-9000 and order the part. The strip is one octave long, it cost under $20, and it's not at all difficult to replace.
As for gigging durability, I've been using a pair of 3000s since the first day they came on the market in the mid-Atlantic region. I have never had to replace a keypad strip or a button board and I perform one to two jobs nearly every day of the week. However, until recently I had a spare strip in my office at all times--just in case. A few months ago, I used my spare to repair a friends keyboard.
Good Luck,
Gary
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Travlin' Easy
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PSR-S950, TC Helicon Harmony-M, Digitech VR, Samson Q7, Sennheiser E855, Custom Console, and lots of other silly stuff!
K+E=W (Knowledge Plus Experience = Wisdom.)