Hi Billman
i had exactly your problem for many years, much to the frustration of our coach. I think i've solved it now (or nearly so at least)
I didn't find any 'static' exercises of any use whatever. I had to dance simple, basic steps and think ONLY of my right shoulder.
Also, and what turned out to be very useful for me, i kept my head high and kept my rib cage well separated from my hips. I found that in this position, it was in fact hard to bring my right shoulder up.
Raising the right shoulder is simply a habit - there is no technical reason for it unless you are trying to pull your partner around with your right arm!
Check out the following - - when you dress and pull on your trousers, do you hunch up your shoulders? I used to, and it was only habit. I worked on that too. It all helps