No Blues at all on 120W Maxspect R420r 16000k

Hi all, I have a 120W Maxspect R420r 16000k. This week, i lost all blues. I have none at all now. It wasn't a gradual loss, they all went together and haven't turned back on since. This seems to be a common problem and I have no problem at all replacing the spare parts myself. I just want to be sure that I purchase the correct spare parts and not have to replace more than I need to.

I've attached pics of the 2 pcbs and the 2 led pads for your viewing. Any help at all would be greatly appreciated. Many thanks.

Regards
Carl