Another weird discovery: With the base 1 and Legacy base 2 hooked up as above in the OP, and since the cab1L only talks to the Legacy base; not the base1, how come when using the cab1L the red light on the old base 1 flickers on and off, just as if you were using cab1?? I am a bit puzzled by this.
I was able to re-tune the unreliable base 1 I replaced using Dale's technique, no problem. The full range of rotation for L8 where it would operate the whistle was only about 1/4 of a turn. And the position I left it in is about 1/8 turn from where I found it, so it seems it was borderline out of tune. Seems to work fine now.
Rod