Elizabeth, I’ve got it ask just in case, but did you give it a little wiggle and a little tap? Is there anything in the receiving slot that may be obstructing the chute? You may need a flashlight to look in there.
Also, check to make sure the chute is not hung up on the positioning ribs towards the front of the opening, and that the chute is sitting flat and flush with the mounting flange.
That’s about all I can think of off the top of my head. I just got my Ego snowblower a few days ago and although it fits fairly tight and snug, the chute does go in and receive the hex bolts properly.
If this doesn’t help perhaps you can post a picture or two showing how the chute is positioned when you are not successful in inserting it?