The pins are knurled on one side, so you need to drive them out so the knurling side exits the receiver first
If you look at a Numrich's schematic it does show a difference on the end of the pin, not the best detail but that corresponds to the knurling.
Brass punch usually gets em started to move. Have done dozens, but one was a real PITA.
Here is where you buy me a beer.............
Putting it back together..........you can come close to getting things all lined up, many times. Save yourself the hassle and make a "slave pin" that holds the trigger group stuff all together, then slide that into place and insert the pins(s).
Had a guy in my LGS work one one for an hr, almost got it, over and over. I went to the back and dug out the slave I made, popped it in the trigger group and had the thing together in seconds.
Good guy, but he still punched me (I used to work there so knew where I stashed it). Been years and we still laugh about it (and he doubles up his fist).