Get a new LNB, they are less than £10 for a 4 port and you wont need to set your dish up, just becareful swaping them. I did it myself, took me 5 mins to swap the LNB then just ran new cable to the other boxes and within 1 hour all were running perfect.
How to install a new LNB:
You need to undo the F connector from the old LNB, this twists off like a screw. You may need to remove the old rubber boot or cut off any rubber sealing tape that has been fitted on the connector. The next stage is to remove the plastic pin from the boom arm and the LNB will simply slide out. The new LNB will slide in in place of the old one or clip over the arm if using the ERA adaptor. Once fitted the LNB is held in place by fitting the new plastic pin through the hole in the boom arm. The next stage is to make the connections to the four ports of the LNB. After fitting the cables pull down the cable shroud. The cable shroud is built into the body of the LNB and is pulled down around the connectors.
Plus all my cabling is outside, no splitters to break down, nice an d neat cabling so my house still looks neat and each box can send its own signal and get its own responce.