I found it a bit finicky and it does take a little pressure. Are you using the stock battery? It was much worse for me when I used the 3rd Party batteries.

 

I had what I think must be the same problem when I first got my DHD. The battery cover was just slightly mis-seated and, as a result, the volume controls were hard to use, even when the battery was removed. Looking closely (through a magnifying glass), it was clear that one of the areas that should secure the cover was slightly mis-formed. In my case I think it was a moulding issue although, for you, it might be the result of slight damage. I shaved the extra material away using a scalpel and this cured the problem.