Check how your trigger pin is installed. Actually, both the trigger & hammer pins are the same part, and there are two grooves cut in it. There is a spring in the hammer that fits in the center groove on the pin to hold it in. With a regular hammer spring, one leg or the other will drop into the groove near one end of the trigger pin to retain it, doesn’t matter which way the pin goes in. Normally.
With your modified hammer spring, the long leg must be in the groove on the pin, so you may have to reverse the pin. If not, the pin will try to go bye-bye!