Replacing Fluvial Chi Light

[Sylvan]

My Betta/shrimp tank is a Fluval Chi tank and I noticed today that the light has stopped working on filter/light cube. Has anyone had any luck with just replacing the light on the cube without having to buy a whole new cube? Looking round Google and Amazon I can only find replacement cubes and since the filter is still working I'm quite reluctant to replace the entire unit for the sake of the light.