I have a 16GB 3GS that had a cracked back casing and broken vibrate switch. It worked fine otherwise. I took out the main board assembly and screen and swapped it into another 3GS that I had around, but now the antenna seems to have a lot of trouble holding on to a signal in places where it worked fine before. I had a little trouble fitting the #7 back on when I was reassembling but I don't think it was enough to damage it.

How would I know if I should swap out the antenna cable (maybe I damaged it) vs just a screwy connection? I tried dissembling and reconnecting the 7 again with no luck.

Thanks!