I assume you've done the blah, blah reboot and you have decent RG6 cable from the dish to the receiver already... If you are hitting one of the main Dish Network satellites (110, 119, or 129), the receiver should eventually identify which sat it sees. No matter what satellite you are aimed at, 70 signal strength is more than enough. I'm confused as to why it is giving you that problem... 125 feet for cable is a little long, but I have seen folks get by with that. Use the zip code calculator to get a rough estimate on azimuth/elevation but be prepared to tweak... (maybe I missed something from sava700 but you're elevation settings could be much higher or lower depending on your location... but they should still be close assuming your mount is level/plum).
I had a similar problem where I was getting good signal strength on transponders but then just got the blank screen like you mentioned. Long story short... it was a bad cable that actually caused certain transponder frequencies to get 'trapped' whereas others made it to the receiver... But I'm not ready to say for you to rip out the cable just yet... Need to rule out some other things.
Can you be more specific about what transponder you have 70 strength... What sat is selected... What happens when you adjust the sat selection to the satellite where it says 'wrong sat' to? Does it lock then? If you have SOME signal strength, did you do a test switch to make sure the receiver is not trying to run through a switch?