Problems with N5050 wireless

Hi I've had problems with an N5050 wireless for six months now. It's been inconsistent and gradually getting worse although the signal always shows as available. I have an N5030 that never has any problem connecting to the same wireless network. I've tried reinstalling drivers. I've tried changing the wireless configuration between WEP / WPA etc... I've updated the BIOS. This seemed to have worked briefly but after about 3 or four immediate connections over 2/3 reboots it went back to being flaky. Typically when I try to connect it fails and I have to plug a cable in directly from the router to get access. If I leave it on it will usually manage to connect at some point over the next hour or two. The windows help messages/troubleshooting make no difference and seem to contain no useful leads. Another curiosity is that usually when it's failing to connect it only lists my wireless network and one or two others but when it's able to connect it lists more from neighbours etc... I've also tried some configuration changes after following other threads but without improvement. Firewall and AV is McAfee but it's no good at an immediate connect rebooted in Safe Mode with Networking which I think I read absolves McAfee from being the problem? The laptop is out of the warranty period, is it likely to be a problem with the wireless card or are there other configuration changes I can try? Thanks Ben