Skybox F5s Skybox F5S

Got an f5 and have used the f3 and f5 but this has a strange issue that gets no signal on certain channels - I have bang up to date channel list as I do my own and use f5 on my system and fine - I have a motorized set up which works perfectly with my f5 and f3 and any other box except the f5s - also I have another dish for another box out back room which will run f5 fine - it seems that the f5s works with some people and not others as im going around different peoples houses trying to find 1 they work with - some do and some don't but only f5 - ive heard about this fix diode but it seems it only applies to the f5 box on 1 of my dishes as all other boxes work fine with both dishes - any light on this - cheers

Ill try but would that affect only certain lnbs as some are no bother at all even the same type in different areas - really weird

I have one, have less signal then cloud ibox...