I was out shooting with my Speed Graphic and 127mm Ektar in a Supermatic shutter the other weekend. After this the shutter has started sticking every now and, either there's a little delay before the blades open, or they don't open at all, or open unevenly. I suspect this is because of cold (it was around -6 when we were outside), but the camera has been siting indoors for over a week now and the problem persists. What should I do?