So you are saying that it is hooked up and working but the picture comes and goes? Is this correct? If not, please explain what might happen if you try to watch something.
What wires are connected to the back of your 920? It sounds like there are too many wires, perhaps someone just used a piece of wire they already had instead of using the proper stuff.
I guess a better question would be, what do you get when you try to use the receiver. You state that the antenna moves well so that indicates that the actuator is hooked up correctly.
Look behind the 920 and see if you have the same wire colors as you do at the dish. My guess is that most of them are not connected to anything back there and you can eliminate the ones that are not necessary.