Ps will look for those nuts and bolts Dan - who knows it could land up being something as straight forward as this so thanks for that!
Not sure if it helps, but I posted a Youtube video of my Audace when I thought it was making strange noises. You can see it here
at about 45+ secs (bike was warmed up at the time).
I was worried that the RH cylinder was much louder/clackier than the left at certain rpm's e.g. 2400, 5000 etc. I did all the usual things like valve adjustments but I came to the conclusion it was just the nature of the beast. I've had it 2 years and done 15000km and it sounds just the same, no worse, no better. Being air cooled and having the cylinders stick out under your ears like that exacerbated any noises. I always wear ear plugs and a full face lid, but with the visor up, it sounded noisy due to sound reflecting off it directly into ear. With lid down I couldn't hear it.