I was watching the Simrell instagram live and he was showing the Vapman condenser unit. He was putting the spiral intercooler in the other end where the mouthpiece goes. He put the intercooler in and then put the mouthpiece on over it. I was thinking about your issue when he was showing that. I...
Wow, you ain't kiddin'. My Swiss mades don't have the logo on the side, so they are newer than yours. Maybe the dimensions changed at some point. You could try putting an Oring to fill in that gap.
I have 3 Swiss models and it fits the middle pieces just right. Ash, Pear, and Walnut. I don't have the gap you are talking about. I do have to spin and push to get it in the Swiss models. It slides right in my Italian. Is it possible your middle piece filter is slightly bent in?