OK. Here is how I went.

There are a few gauge changes in 727-100 v2.4, I replaced them with the ones from v2.3, one at a time, then in different combinations. Each change required FSX to be closed and then restarted. It was a case of: Make gauge changes, start FSX, load CS727, Fly, FSX off, make gauge changes, start FSX, load CS727, Fly, FSX off...over and over again :D). I never got the sound working that way. I always had to reload the aircraft. No idea why.

So...... I went back to CS727-100 v2.3. Start FSX, load CS727, fly, no sound! What???? No matter what I did, I had the same problem. I had to reload the 727 to hear the sounds.
So.......I went all the way back to v2.2. Start FSX, load CS727, fly, no sound! What on earth is going on here? Same deal as v2.3 and v2.4.

The only thing I never did, was the editing the registry. I really don't want to do that.

Mark