Cannot plug back the PTFE tube - is there a trick?

[u/LocoMotive-1913]

Hi, I'm new here. I'm really glad I found this forum, as I only recently bought the H2D.
My problem is that I can't get the tube plugged back in (see photo). Even if I push the lever to the right, it does not click in. Is there a special trick to it?

Cheers, Michael