I have to agree with the others here. I'm not saying that this is what happened in this case but I see this sort of thing quite often at my field, someone dumb-thumbs one in and blames it on radio or equipment failure. I'm sure this reason gets VERY old for Horizon and all the other companies out there. Just out of curiosity, if the elevator servo "locked over solid" as you put it, wouldn't that have caused the plane to loop several times in 400' before it went in? Seems to me it would not have headed straight down.