No signal at all on input 2 is bad.Have you tried unscrewing the cables from the back ? When mine lost one signal,the reason was a split in the sleeving of the cable outside had allowed water in and over time the water got in the back of the box and blew that signal.Unscrew the cable,if it is a healthy copper then its not that but if its black then it is !
Also,you could simply try swapping cables and seeing if anything changes ie if the other signal drops out but the signal 2 is fine then it would point at the cable being at fault.
Post back with your findings.