Changed screen, low signal?

[061189ji]

Hi I recently changed the screen on my G2, however I'm a bit paranoid because i feel as if my phone signal is not as good as it should be, perhaps due to incorrectly putting the phone back together. I am however on a new network (three uk) so I'm not sure how it was before (i bought the phone broken off ebay). That being said three do tend to have bad signal in my house. I wanna know if it may be due to a bad connection in the 3G attenna from bad repair or if the network is bad, normally get 0 or 1 bar 2 if if im lucky. Three if i go outside or near a window.