Medium Bell Siphon for 4" Media (new v2)

The product design seems nice but the bottom part is two 3-D printed parts that screw together and the threads from the top part don’t seem to engage the bottom part. Well they do engage but one screwed tight they will slide back down the threads and have to be re-tightened again. I was able to make it work using some silicone Around the base but the tolerances for the threads on the two 3-D printed parts. I don’t think are adequate.

The paper that came with it says one thing and when I messaged them about it not working I was told something different. But they did get back to me quickly. Only problem is that I already drilled my tanks for this size siphon.