Anybody ever tried this little gizmo?

After your back heals up, try it without the check weight. Or because it can be difficult to get the weght out, loosen the nozzel screw a couple turns. I had a nozzle that wouldn't squirt and ended up grinding a little off the bottom of the screw. Some require a hollow screw also. Good luck.
I found out what the issue is. I emalied BLP and let them know the issue I ran into. They said I was sent some first generation nozzles that are shorter in height and allow the retaining screw to bottom on top of the check valve. They're sending out some newer ones at no charge, and said they would even send some more if I wanted to return these that I have. Can't ask for more than that. So we'll see how these work.