u/532ndsof

Hello all! Hoping you can help with a puzzle I have. Recently the cover on our dryer vent mysteriously disappeared (I suspect a casualty of some yardwork we had done recently). I would like to go ahead and replace it but am having difficulty. I picked up a standard 4" cover from the hardware store but the attached 4" tube won't insert into the ductwork here. I suspect the square base I'm seeing and possibly the opening are part of the old cover when it got broken off, but the tubing seems pretty firmly stuck in place. I don't want to overstep and somehow start pulling out ductwork or something. Any advice on how to proceed would be appreciated!