I checked the 20A underseat fuse (fuel pump etc) on my bike the other day and the plastic casing of the fuse had almost completely melted off, still working though.
I replaced it and put some silicone grease on the contacts of the new one - I guess that 10 years of use had overheated it but I'm glad I found it before it broke (there was not much holding it together).
Just a heads up to check these things occasionally.
