Specifically for me today, a pin punch and fairly heavy hammer. I usually put one of the factory, extended model 34 slide release levers on the other models. Have done the job maybe 25 times now, for myself and tinker-phobic friends. Usually the trigger pin will push right out with even a plastic punch; once I needed a few taps with a small hammer to complete the task. Today I met a model 17 with (presumably) an oversized pin, and undersized hole in the frame or internal part. It took several whacks with a 16 ounce claw hammer, and three or four F-bombs, to get the pin going. I've heard that can happen but was always skeptical.
Maybe this would be a good thread to share similar stories of Murphy's Law comes to gunsmithing. Jump right in.