loctite? i havent come across any on a carb as of yet.. maybe someonedid mess with it.
i've seen 3 stock mufflers and on all 3 the little tail was slightly crimped, just like yours. First thing i did was open it up but it makes no difference.. I'm thinking it is done at the factory.
Then i cut open an exhaust. There's a much smaller tube that ALL exhaust must pass through inside the muffler. Access that tube through the large bolt under the right side heat shield.
If you can't stick a screwdriver straight in the bolt hole exactly 5 inches or more, you havent completely penetrated the carbon in that tube.. The screwdriver is either hitting the baffle wall or the tube is still clogged. Carbon does not collect to any apprecialble degree anywhere else in the muffler.