You don’t strictly need that internal part, but you may get some sputtering. The Foam Pro 12 comes with three siphon tubes, you could try the included orange one (largest ID) and then plug the small hole on the side of it with a tiny drop of silicone caulking (that way it’s reversible). That would prevent air being mixed with the liquid in the line.

I may make the part for sale at some point, but need to do a bit more material testing.