I have the flock roller how do you get it on the handle?I try pushing it on and it only goes 1/2 way?Is there a trick to it? Comes with no instruction

We slid the roller on as far as it would go, then tapped it like a hammer (very firmly) on the floor a few times until it slid all the way on.

There is no trick. It should slide on the frame. The only resistance should be when the wire frame engages the bearing inside the roller, but that shouldn't be too noticeable.