I feel like an idiot for asking this, but........... Is there a trick to using pumps designed for presta valves? My old pump had 1 head & needed an adapter for presta valves. Lately, I had trouble making it stay on the valve, so I just got a new pump with dual heads. I was excited about not having to use an adapter on the valves thinking it would be easier & simpler, but I have the hardest time, getting it off the valve. I'm afraid I'm going to rip the valve off the tube. Also, it seems to let a lot of air out when it comes off, but that may be pressure built up in the pump hose itself. I'm tempted to going back to the adapter & use the bigger head. Any ideas?

Dan