You are basically doing fine. After a lot of times handling if you can't get a good initial line try moving up some for the blind. He should have a good idea of where it's at so try a few steps in that direction see if he doesn't focus a little better. I've moved up all the way to even with the gun station to get them to look down at the pile. Next time you do one remember you had trouble with the last one so set the diversion further away from the line to the blind. You need to be able to handle off an old fall so you aren't going exactly going backwards if you need to handle off of it sometimes. But you also need the dog to understand that he is on a blind and not going back to an old fall.
I have been sending him and then handling him off, but it doesn't seem to be registering that he needs to go straight to the blind without the detour toward the bird. I understand that you initially don't need to fuss with the dog about the line, but when do you start insisting on a good initial line to the blind?