I like my 4dtv a whole lot better than the old Uniden. Any satellite you have programmed in under a KU name (X4, XB, B6, K5) will be all KU. Try K5 and K3 for some channels as well. B6 usually has some good analog feeds too. The 4dtv remote, press the down arrow key and a box comes up at the top that tells your polarity, actuator position, and skew. You can play with this to figure a little more out on that. You get the best pq with the RCA jacks, I hate my channel 3/4 inputs. Although I have a 922 and yours is a 920, the only difference is the 920 doesn't receive some of the showtime channels on C3/G0. Also, do some research on using generic satellite tiles (CF, CG, CA, CE) you will really like that too, but wait til you learn the box a little more.
Also don't be alarmed, but if you ever connect your 4dtv to a dish by itself, when the 4dtv sends the power out to the dish, the receiver will click, once when it starts to move, and once when the dish has stopped. I thought I had messed something up when I heard this sound.
G1-3 shows the 'Can't find channel, blah, blah' message because this transponder is a digicipher II transponder, all you will get is this black screen. But this is where you need to go to get your maps, rehits, guide info. There is an option in the dish settings I think that says 'do you want dish to move for updates', select yes and every night after 2am the dish will move to G1-3 or G1-1xx but the box has to be off for it to know to move, however, you do not have to turn it off if you are going over to G1-3 just to update or rehit the box, just move it yourself and wait a couple of minutes with that old gray screen. Also, if you are on any other satellite and scanning the analog channels, and you come across that black screen--its only because that is the transponder that hold whatever DCII channels on that satellite. GB has quite a few of these black screen channels, so don't be alarmed and think your box isn't receiving analog.
IMHO, this is the best purchase I ever made. And for you, $20 isn't bad at all my friend....good find!