Building up a bolt completely from scratch parts, attempting to insert the safety selector into it's mating part, I can get the small plunger on the selector to move/compress with a small tool/driver but can't keep it depressed enough to slide it into it's mating groove...just not a lot of room to work with (in contrast inserting or removing a magazine cutoff is much easier...more room to work with).

Is there a special tool to do this (which of course I don't have!) or some other clever technique?? Thanks!

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