What are the parts most likely to go bad first?

[Peeking Turtle]

New to being a Bueller. My brother just gave me a 2009 XB9SX with 21K miles on it. What a score! It's been well kept, looks good and runs great. The only maintenance I've done is to replace the belt and spark plugs. I also took off all of the aftermarket turn signals and mirrors and installed all original stuff. Sanded off some minor corrosion on the tail and painted.

I've been reading a lot of the info on this forum for weeks. I'm hooked! So much good info. Installed ECMspy and got a Buelltooth. Would've done the ECMdroid, but don't have an Android device.

My question is if I wanted to keep a box of parts most likely to go bad first on this bike what should it be filled with? Not talking about routine service stuff. I have some idea of what to fill it up with, but I figure you guys would have much more of a clue as to what goes first on these bikes.

Thanks

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