I'm experiencing similar problems. The coins in the can, the party whistles, and regular whistle stopped working. Himalayan chews work, but it isn't good to chew on those all day, every day.
I have resorted to the spray bottle with water.
So far, so good. I've only sprayed twice. Maximo thinks I'm spraying something mysterious on him. Now all I have to do is pick up the bottle and say, "Do you need some no-bark spray?"
I'm going to try using a squirt gun on our walks.