So I have been in shock with my year and a half old lab over the last 2 weeks. So here is what's going on. He is currently a JH titled dog and never had a problem running on marks. Two weeks ago he started going out half way to the thrown mark and just stopping and staring at the area where the mark landed. If you call him back to heal and send him again he will go right too it but obviously thats counter productive. He wont stop on live birds but will on dead ones. So here is what we have tried so far. Shortning up the marks, holding him longer at the line, letting him a little lose on the line, Putting him away and not letting him have the mark after he stops and having the thrower hollar for him "Seems to work most of the time". So has anyone else had this problem if so how did the correct it?