A few days ago, I noticed that my throttle grip was sliding around on my throttle barrel. Here's what I did to fix it. I took an empty toilet paper tube (not the most fancy repair material, but hey, at least I'm recycling lol) and cut it to fit inside the throttle grip. I then squirted a few beads of superglue over the throttle barrel and slid the throttle grip on with the toilet paper roll inside it. The throttle grip grabs the cardboard much tighter than it grabbed the throttle grip, and the grip itself is not glued to the barrel, only the cardboard is. This way, should the grip ever need removing, it should come off with a good yank.