I could only find the original Emil Flues patent drawing. It appears that the firing pins do not have return springs. It's possible that there may be a bit of dirt or rust in the pin bores, preventing the pins from freely moving back in to the breech. Why don't you try putting the smallest drop of oil on each firing pin and then gently push them back in to the breech face. Does the dragging occur with all ammo, reloads etc.?