sky hd thompson box how can i fix input 2 lock indicator not locked?

I have recnetly lost some channels and it would appear that signal input 2 has lost a connection. I have swapped the two input leads to see if the situation changes but it does not therefore I can assume it is a box problem and not a cable problem. Is there anything I can do? The box is a thompson SkyHD box 902020 version 4E3006 operating system version 1.32B12 EPG software version sky+8.3.2