I have the same problem. And at least for me it's the handle that allows you to turn on dashboard lights and so on that's the problem. Because i guess he as well has to wiggle it abit to get the lights on and it often goes out when using the turn signal, right?
I tried dismantling it and soldier on a bit extra to make a better connection between the copper plates (inside the handle), when mine stopped working completely. it seemed to temporary fix the problem, but now it's back.
What's going to be my solution is just to make a "night mode" button and remove the dimmer, since i only use it with full dashboard light anyways, Just gonna make myself a wire diagram first. (Unless someone already made it.)