[Kymmy]

Chris remember that the channels are not done via a singla sat but many which are constanly in motion inside a virtual box and also the transponders point in slightly different directions, both of these things mean that some channels can be a lower signal strength than the other.. Always best to tune in the sat/point the dish using the lowest signal possible, if you suspect the cable then replace, the LNB's are normally sealed so shouldn't be an issue there..

Also have you properly orientated the LNB in it's holder for your latitude?..