I'm in the process of replacing again the cambelts on my 996 (V plate/2000). I've bought OEM belts, as usual, but I've also now purchased a Facom DM16 belt tension gauge (in the past I've relied, successfully, on the 90 degree belt twist). But I'm confused; the pamphlet that came with the Facom says use the Number 5 button, but various videos on YouTube recommend the Number 4 button. So 4 or 5, and is it really that critical?
