Smith M64 Revo Issue

[Caleb]

I have a Smith model 64 revo with an issue and would like some suggestions from yoos guys. When cycling the revolver, sometimes the cylinder stop does not disengage from the cylinder and basically freezes the gun till you release the trigger. I had this issue since I got it and went ahead and changed the cylinder stop spring with a Wolff unit. This worked perfectly for about 150 rounds and it started hanging up again. I have noticed that if you pull the trigger slightly sideways while pulling back, it will hang up every time. If I carefully pull the trigger straight back, it works every time. So, do you think I need some kind of "shim" on the trigger, a new trigger, or what say you?

Thanks in advance, Caleb