My Stoeger isn't firing correctly. When I pull the trigger for the right barrel first (front trigger), the left barrel (rear trigger) will not fire the round. When I do it the other way around, rear trigger then front trigger, both fire fine. I've owned the gun for a few years, but it hasn't been exercised in some time, but I generally pull the front trigger, then the back and I don't remember having a problem before. I've read other places that there is potentially a firing pin or mainspring issue with these guns anyway. How do I determine where my problem is and where would one get parts to repair it? I'm not a gunsmith, but I'm mechanically knowledgeable, and a simple part swap cannot be that hard on something as simple as a double gun.