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.
------------------ Travlin' Easy
PSR-S950, Bose L1 Compact, TC Helicon Harmony-M, Digitech VR, Samson Q7, Sennheiser E855, Custom Console, Morgan 33 Out Island Sailboat, and lots of other silly stuff!