Anyone else having problems with the newly desinged muffler on the US Engines 41CC?

After flying 3 flights on a NEW engine the muffler was loose. Here is what I found:
1. The aluminum muffler block is threaded.
2. The gasket was totally destroyed; only the metal remained.
3. I removed the old gasket and it appears the bolts do not draw the muffler up snug against the exhaust port on the cylinder.

My fix for now is to remove the threads from the muffler and get a good metal to metal match. Then install a new gasket and try again.

Any suggestions?

Garry