We ran into this today at RevSpace (Hackerspace Den Haag). The tube was bent and the air assist got blocked.
I found your 3d printable guide, but didn’t want to 3D-print. I prefer laser cutting, and it was just as easy. I just cut a circle with a 10 mm radius (20 mm diameter) from 5 mm acrylic, with a few holes for zip ties. I don’t know how long drawing, cutting, and installing took, but it was faster than typing this reply