Thanks for all your advice Shawn95GT. I think, however, that I may not be able to use a dish after all. I've tried everything, with no luck. I went out and bought a compass, so I could get the azimuth down to the degree. I have the elevation correct too. Still, no signal from the AMC-3 bird.
I think the problem is that I live in front of a line of trees that's blocking the path to the satellite. I just assumed that I'd be able to use the dish, since my neighbours all have dishes, but I see now that their views aren't being blocked the way mine is. In addition, this grouping of trees is quite dense. Unfortunately, however, they are not on my property so I can't do anything about them.
Is this the end then for me and satellite systems?