I don't know if this will help ( Think I'm right on this ) I am not sure what to call this part but if you remove the grips, since this is a j-frame like my 610 and should be the same, there is a piece of metal that is in the handle and there should be a tensoning screw that impacts the trigger pull. I was getting light strikes on my 610 and found that the heavy recoil on full velocity rounds, at least that is what I think, had caused the screw to back out and thus caused the light strikes. I screwed the screw in and found a place where the trigger pull was still good and no more light strikes. I think that you are to screw the screw in as far as it will go but it did impact on the trigger pull. Don't know if this will help or if this is the problem, but thought I would mention it. Good luck on solving the issue