Yes it is a problem on the
X6HR as well. I have found that if I use a nickel in the slot it works best. If you keep on turning counterclockwise with some force that usually makes the cover pop off. In those rare cases when this has not worked, I have used a fresh razor blade to help pry a little. In any case you should replace the gasket and the cover with a fresh one, you can usually get a kit from REI for under $10.