Those more precise movements do wake the dog up and require more attention. When I get the attention, I help the dog find the right spot. I may guide, I might use my hand to draw attention to the focal point. As soon as the dog is correct, I mark that. If the dog is more accomplished and I feel that we can get several steps of correctness, then I really let the dog know that it is in the right place. "that's it! really nice! good job!" in a very happy and admiring tone of voice. The manuevering makes them engage more and then the praise of correctness... they seem to understand this is what is wanted.
I am not saying this is what you particularly are doing... but I do see this often. People work to get the correctness and then when the dog gets it right they seem to take it for granted and keep going. If I am struggling for particular picayune position (to the dog), like in heeling, once we achieve it I really do make a marked change in my interaction with the dog as we are moving. Stopping to mark it each time results in very little heeling practice, so the bridge communication is very important.
If the dog is not "finding" the right place, I might even just hold physically hold them there. Sometimes I am phooey on shaping.