Rocket 2020 Gt - Front Mudguard Ratttle

Although I never experienced what you describe I did notice when cleaning the front mudguard could make a noise as if something was loose
So I removed the four Allen bolts that hold it on
Then you have to push it towards the engine and it comes off
It’s then that you can see two sockets on the inside of the mudguard where the mounting tangs sit
I put some silicone sealer in the two little sockets and refitted the mudguard and left it cure
The slackness was then gone
No more noise

 

You can’t see it once it’s done so the colour doesn’t matter
I just used a general bathroom type

 

I've noticed this on my TFC, not so much when riding, but when I stock, and sling the stock over to the left (so that I can press the electronic steering lock), as it hit full left lock, the mudguard twangs.

I took it to my dealer, and they investigated and said it was 'normal', and blamed the fact that the front and rear wheel are offset laterally (which, to me, doesn't make any sense, but hey ho). It also irked me that on another TFC they still had in the showroom that hadn't been collected yet, it didn't exhibit the same issue. So I'd hazard a guess that most (but not all) Rockets do this.

I'll certainly also have a go your solution @dilligaf, cheers.