Try taking the sear spring out and see if the rough spot goes away. That will tell you if it's the disconnector because it will just stay down in the frame.
I know this sounds strange but changing the bushing got rid of the binding in the Colt/Wilson combo. This particular one is an oversized barrel so I had to open the ID. a little. I still think there may be a link problem but I haven't figured all that out yet. Still won't hand cycle jhp's.