They should slip in with your fingers, eyeball them to center them, then the floatbowl should prevent end play. Then in use the gas varnish will stiffen them up.
Keep in mind too if there is a burr or flare, going to need pressure to install...not so good.roll the end thru a finger and thumb with light pressure on it..should feel if uts flared or burred.. The end going in should be smooth and round.