Taff, if you have one of the Gen 1 Sky HD boxes (All made by Thomson if memory serves) and not a very recent Gen 2 box (Gen 2's come without the component output) and you are getting failed recording/ input 2 losing signal/weaker signal than expected when compared to the + box signal, then you are showing all the sings of the standard Gen 1 pants PSU syndrome (and breathe...). On AVforums there is a huge thread about this, which have posted in too with my experiences. I will take a gamble and link to my original post:
http://www.avforums.com/forums/showthread.php?p=6501961#post6501961
Our 2nd box was awful almost from the start as that post will show. Instead of paying Sky £65 to get a second hand box which would most likely have the same problem I got a modified PSU from Satcure. Although you could get Sky out free, you will still get a second hand box and they will walk away with your new one! Personally I would take a gamble on the beefed up PSU and keep your new box but that is just me
http://www.satcure.co.uk/accs/page12.htm#rebuilt is the link to the improved PSU. It is a doddle to fit and if you keep your original PSU for warranty purposes it will cost about £60 if memory serves. From the very day that I replaced the PSU with the modified one we have not had one single failed recording, lockup, lnb signal failure, power down or anything. It has been bulletproof for 4 months and I cannot recommend it highly enough. Just so you know, none of the caps were showing signs of bulging like the psu was still the cause of all the problems I had.