Removing tube from EE Minimax Dac

I feel a little silly asking this question, but I have owned a lot of equipment with tubes over the last 20 years and have never run into this problem. I am having the hardest time pulling the tube out of my Minimax dac. The directions say pull and don't twist. I am pulling with a good amount of force and it doesn't budge. Any thoughts from Minimax owners. Thanks