Another day of working with the whistle and the learning curve is there for the both of us to be sure!
I'm still trying to make my signals consistent so that he can have a clear signal to pick up on. Meanwhile, he's still get used to the concept that he won't hear my voice give the signal and that he can't just key off my body or movement to get 'hints' on what to do.
That said, I did give the voice cues in an effort to teach him what the whistle sound means. That seemed to work before, but tonight, it seemed to regress a bit. After getting some mixed results and starting to see a few signs he was getting confused and uncertain, I decided to try another strategy.
Since I have a hand signal for staying while walking with me (he stops while I keep moving) and for the 'front' (where he comes from where he is to sit directly in front of me), I decided to throw those while giving the end of the whistle signal. So the stay-while-walking signal get tossed out while the long signal tweet is going on and the signal for 'front' comes just before I stop the third short tweet.
This seemed to make more sense to him and he started to respond more quickly and more sharply. He didn't look confused either and I saw that eagerness in him pick up again. While this might have been something of a set back, it's things that let us find more ways to communicate and work together so he can have success again.
One behavior that's still strong is the 'stay' while he's going after something. I did it twice, got him all hyped up and send up to go 'chase' something (there wasn't anything, but he went out and was searching for something and sniffing and all that), and then I gave the 'stay' whistle, and he stopped and looked at me. Great! Then I took the chance to bring him back with hand signal + whistle strategy and he came back nicely. Maybe we're on to something on which we can build on.