Very often DRL's become dull. This due to the reflective paint in the light wearing with age. It is only a chrome paint. As it wears off you are left with just black plastic. A cheap & easy repair is to clean the plastic, then stick some aluminium sticky tape into the reflector 'bowl'. It is a bit of 'bodge', but once the lens is refitted only you will know & brightness will be restored to 'as new'