Have you looked here?
ITC-Lighted Handles
They sell handles and the bulb.
Mine was in bad shape but the company that made it (ITC) had moved on design wise and I couldn't find a matching part.
I took it apart. The top end with the bulb is just pressed on. The other end is glued so I had to cut it off and repair it because the metal ends were corroded. Ground away the naughty bits, filled with bondo and repainted. Wasn't ever going to be chrome again. Installed new light bulb, too.