The shroud around the muffler on my fastrack 44 with kohler 18hp. is rattling like crazy on start up. After the unit gets hot it seems to settle down quite a bit. I had the shop check it last winter during my annual PM but they said everything we tight. This last weekend it seemed to be worse and I put pressure on the shroud and the rattling stopped. Is this normal or do you think I have a broken bracket? I did not see anything that looked cracked or broken??