Is there such a thing as a friction spray? and no I don't mean glue or duct tape(!!) I've a mounting bracket that screws together to tighten it up, but the previous owner has ruined the screw head so I can't tighten it any more so it keeps falling down with the slightest bit of weight. I wondered whether there was a spray or such that I could spray between the two pieces that would create some friction enough to hold it stationary, yet still enable it to be moved if required. Almost like two pieces of sandpaper. Trouble is I can't take it apart to access so it would need to be a spray of some sort.