How can I get the light to stay on my Darth Maul Lightsaber?

I just learned about the recall. However, it's a tad bit late. Anyways, when it gets hit, it lights up and it still makes the humming sound. Does anyone know how I can rig it or fix it to wear it lights up all the time? I have Qui Gon's Lightsaber and Darth Vaders.