A Little Help Please.

I just finished repairing this beautiful silver trumpet made in PRC, wherever that place is. Well, for some reason, it isn't playing very well. If anyone can help me, I have just about given up. Maybe it's just me.? I should probably just bill the customer, and return it. I'm sure he won't have the same trouble with it that I'm having. So before I return it, I'd welcome any suggestions on what might be wrong with it. When I play, it sounds a little ... I guess I would have to say, "airy". But I haven't been playing much lately, so....

Thanks for your help,
Mark