SA failure to reset

[Burger_King_Taco]

I have a 75 SA frame. FPB delete on the slide, shadow sear, shadow narrow hammer. The trigger bar return spring has plenty of pressure on the trigger bar. The SA trigger has both set screws removed currently. The gun dry fires perfectly and always resets.

 

When firing at the range I can only get 1-3 or so rds before failure to reset. The hammer locks back on the sear, but the trigger will not drop the hammer because the trigger does not actuate the sear. Once I was able to get an audible "click" reset by pulling the hammer back more - which allowed me to fire the gun. This is occurring about 50-75% of the time. 

 

I am able to resolve this issue by doing the following: with the failure to reset and the hammer cocked and locked into the sear, I can use the tip of my knife to press on the sear thereby getting that audible click, which then allows me to fire the gun. I can also remove the slide and with the gun's failure to reset, but with hammer cocked and locked into the sear, I can press down on the sear cage (there is a slight gap between the rear sear cage "fingers" and the frame shelf that the sear fits into), by pressing down on the cage I get the same audible "click", which allows the gun to fire.

 

Any help is appreciated. Thanks!