How do I stop noisy mudguards rattling?

Need ideas of a way to stop my my guards bracket rattling. I have SKS mud guards on my bike which Evans Cycles did a good job of installing for free when I bought my bike a few years ago. They have been excellent, especially during the last two winters. When I first saw them on the bike I was convinced they would come loose and not withstand the harsh conditions, only as they are so light and minimal. They have far exceeded my expectations and even survived knocks and crashes. However one slight niggle I have with them is this metal bracket which attaches them to the brake bridge on the seat stays. The bracket is never truly permanently attached the mud guard the mud guard instead just sits loosely on the bracket. Therefore the mudguard constantly rattles in the bracket which is quite annoying. Looking at the Evans website I can see that on the newer versions the bracket has been replaced with a permanently fixed bracket which won’t rattle. Any any simple and discreet ideas of how I could stop this bracket rattling? If so let me know by commenting below…