Casoli market a red/white/green (a la Italian flag) coloured bezel for the tacho on F4's and Brutales. In order to fit one of these you need to split the instrument binnacle itself, which is just a few cross head screws holding the two halves together. The actual tacho needle then needs to be removed. Has anyone done this? I'm wondering if its just a push fit on or whether there is a keyway or splined shaft arrangement.