I just made my first flight w/ my Nextstar last Saturday. After about 5 minutes of flying, the engine just quit. My friend took over w/ the buddy box and brought in safely. After inspecting the plane, I saw the exhaust deflector fell off sometime during the flight. Would this cause the engine to quit. We coudn't get the engine to run w/o the deflector and I didn't have a spare. ( BTW the engine is an OS 46 FXi and I'm not sure about the muffler. Whatever came w/ the engine.)

Also, I couldn't get the fuel to drain from the tank when I was packing up.

When I got home, I took the engine off the plane and removed the fuel tank. I couldn't find anything wrong with the tank or tubing. When I reassembled everything. I decided to reorient the muffler away from the plane a little more.
When I took apart the muffler, a cone shaped plate fell out & I didn't notice which direction it sits in the muffler. Is this the baffle? Does it point towards or away from the front of the muffler.

I know there's alot of questions here, but any help is appreciated. Thanks.