Question Rgb fan problem. Roughly 1/4 of one fan led stopped working

[mdoliveruk]

I have managed to get all my 4 rgb fans working and connected to a controller. All was well and I had full control of them and all worked great. The next day one of my fans has from 12-3 (clock face) seemingly dead leds.
These are thermaltake rgb with aio
Any ideas would be great!