The signal strength on my 3GS became intermittently poor until it finally said No Service permanently. The phone was jailbroken on 5.1.1 and 06.15.00 so I restored it to the un-jailbroken state and restored the old base band because I'd had No Service issues while jailbreaking and thought that might be the problem, but it wasn't. I fitted a new antenna/dock etc. assembly and it worked fine so I jailbroke it again. It was perfect for 2 days then No Service again. I opened it up to check that the antenna was connected OK, which it was. I also checked that the gold contacts from the logic board and the antenna are in good contact with the bezel, which they are, so restored it again, this time to OS6 and still No Service. Can the new antenna be faulty? What can go wrong with it? Is there a method of testing the antenna and its connection to the logic board with a meter? Has anyone published any data on individual component testing?