You are doing the absolute smart thing by having your experienced friend check it out and take the first flight. But there is one thing you said in your post. I will fly it around and maybe
the noise will go away. Never ever take off with a small problem and hope that it fixes itself while in flight. Mostly small problems on the ground turn into big problems in the air. Good luck and pretty soon you will be the one giving a check ride to a newbie :idea: