
I have found going forward with ntheri head up at a fat pace and then slowing down into correct trot soes the trick.
For a dog that can pace fat it is a case of teaching them that you do not want this laziness, as has been said it is a comfortable gait.
To do this use a word like Walk or trot. Move of briskly, and if they pace go back to the start. You may find you do this 10 times, but the dog will know that when iut trots you will keep going and of course get lots of praise.
I ahve used both techniques for my old girls, and she quickly learnt to do the correct thing. At the begininnig if I ever felt her start off wrong I would go back to the start in the ring.
A judge would much rather you realised your dog was wrong after a couple of steps rather than you doing a whole circuit wrong and them either asking you to do it again, or dismissing you in a large class from a placing on poor movement. Same goes if you ahve a naughty over bouncy pup, go back to the start and they realise being silly will mean repeating it over and over.