Mine leaks like a sieve!

The 15GX2 gas (pumped carb) one piece muffler is leaking from half way down the muffler. I cannot see how to dissemble.
The manual shows a through bolt with a nut etc but my muffler looks to be a single peace with no nuts holding it together.
It is leaking from under the metal band half way down the muffler, the engine mount has sealed really nicely, so the gunk is not coming from there.
Do you know how to fix the leak? I am assuming I should be able take the muffler apart and seal, but I cannot see how to dissemble.