I have also had issues with taillights falling off. So, finally, I just wheeled my bike into this awesome hardware store in my neighborhood (Pearl Hardware) and marched it straight back to the guy with the nuts and bolts and stuff. I showed him my Hotshot 150 mount and he made a couple hardwareish remarks about how Cygolite didn't quite have it optimized. Anyway, he grabbed some hardware and a couple tools and in about 6 minutes, presto, totally, insanely secure taillight. Cost me less than a buck fifty. Don't understand why I didn't think of this a few years ago...