An opening lever left of center is not always an indication that a Smith gun has "shot loose"; but instead evidence that the original top bolting device is performing as designed, taking up normal wear from the binding of two metal contact points. Most double guns become loose due to wear at the hinge pin joint (the round pin in the front of the frame upon which the barrels hook, their contact point with the barrel hook forming the hinge upon which the barrels can move up/down on opening/closing). It is common for guns with a lot of use, and sometimes not much use but a lot of abuse, to see wear at both the hinge joint and at the top bolt. Either can usually be corrected by a skilled double gunsmith without damage to the gun. In the case of the tapered top bolt, the bolt can be replaced with a new bolt and the opening lever refitted; or many times a gunsmith can judiciously add small amounts of tig weld to the bolt, top lever, or both pieces and carefully work those surfaces with a file until they are restored to original correct tolerances. With badly worn hinge pins, it is sometimes required that a pin be replaced; but in most instances a competent gunsmith can judiciously tig weld a small amount of new mental onto the barrel hook, then carefully file same to the correct tolerance and radius, placing the barrels back on face to the frame. What I recommend you do is have a competent doublegun smith check your gun to determine where the wear areas are, and prescribe the correct repair. Going forward is it most important that these areas of wear be properly maintained to increase long-term serviceability of your gun. I suggest the judicious use of a high quality gun grease designed for hinge and bolt joints. When cleaning my guns, I always finish by taking my pinky finger and rubbing a thin coat of hinge joint grease on the barrel hook, the knuckle of the frame at the joint of the fore iron; and on the rib extension, being sure to have ample grease in the tapered rectangular slot that receives the rotary bolt. Good grease will do wonders to reduce wear on these bearing surfaces; but don't overdo the gease, and be sure to wipe off any excess once the gun is reassembled. Another trick that will extend the life of the rotary bolt joint is to never snap or slam the action shut. Keep your thumb on the lever and allow the bolt spring to lock in position normally.