OK As we work through this, the gun may have several problems. LOL
Took the grips and side plate off.
As I played around with the trigger, the stop is at its high point when the trigger is fully pulled and it is then high enough to almost catch, but not quite. It will scrape the bottom of the cylinder. As soon as I release the trigger it falls back down to its "normal" low position.
I tried to push the stop down with a screwdriver and it wouldn't move at all when it was already down. With the trigger pulled and the stop "high" i could push it down and it would return to "up" when I released the trigger. Just not up enough to catch and hold. I'm assuming the stop is trigger driven because one I hear the hammer fall, the stop stays high as long as i keep the trigger pulled. Once I release the trigger it falls.
Then something else happened. The trigger froze up and as I played around with the trigger and the stop, 1/2 of a part fell out. LOL From the diagram you supplied it looks like the left end of part 468 (split spring). I don't know what happened to the other 1/2 or if it is still in there somewhere. Could the split spring be the whole issue, or just another problem to fix?
Thanks