I think I posted about this before. When Dylan was a puppy, he was barking and lunging himself at the vacuum. What I did was I left vacuum running and starting to play with him with his toys around the vacuum. He was little hesitant at first, but eventually caught on vacuum equals play. Now whenever I vacuum (which is everyday with his fur flying all over my place), he brings his toy to me expecting for a play. I don't have to play too much. He gets bored knowing I pay attention to vacuum more than I do to him and gives up to go sleep on the couch. When I got my maltese, she barked at the vacuum initially, but soon realized Dylan's abosulte disregard to the vacuum and stopped paying attention to it too. Now she just sits and watches me vacuum. So maybe you can associate vacuum with play. You should find something your sheltie loves to play. It has to be more interesting than vacuum. Good luck.