I have this little 3" long and 1/8" square super strong magnet that I put on the bottom of my frame for the same thing. Once I attached it, or should i say, it attached itself, the sucker will not move and ain't going anywhere. It actually works great. I have a troublesome intersection and this cured the light trigger problem.
Darned if I can remember where I got it though. Cost about $12 I recall though.
