fixed mine by bolting it to an old lupine bar mount. I used the alloy helmet mount that comes with the gloworm light, drilled a hole in the flat plate part and bolted this to the lupine bar mount using the hole in the mount that attaches it to the lupine light head.
I dont intend using the light on a helmet so this works fine with me, and even if i did decide to mount it on the helmet its only one bolt to undo. Its very secure now, no wobble at all.
I think gloworm just need to alter the fitting side of the bar mount so its a bit wider, and use a more rigid grippy rubber strip rather than the foam, + a stronger O ring. (ie just make the underside of the bar mount like a lupine one!!)
You could do the same with the Hope mount as well, just drill the flat plate part of the helmet and bolt it to the hope mount.