Cyanoacrylate gel has been known (to me) to work. It has been known (to others) not to. Low temp solder and flux paste probably better; maybe Swif 95. Either way you need some sort of steel round bar for a caul or negative of the shim you're trying to hold in there (Mike Orlen uses round transfer punches which come in sets and provide a selection of diameters to suit). Need a C or bar clamp. Need a heat source if you solder. Need everything clean and degreased whatever you do. I don't think a little "tooth" accomplished with sandpaper on the back side of the shim hurts. Maybe you need water in the barrels or a wet rag on the bottom rib if you solder it. Need to make sure you're not putting more shim in there than you need.
jack
