My Kaweco Lilliput has started to leak A LOT

So, I have a Kaweco Lilliput Copper that I have used for about a year as a pocket pen. I love it, it is aesthetically beautiful, and also very small, so very convenient with the small pocket book I have for quick notes etc.

What I have noticed over the last month or so is that it has suddenly started to leak quite a lot.

Thankfully it does not seem to leak outside the cap (which fits very solidly and snuggly) so I have not suffered any ink onto my clothes, despite it being in my pocket, but when I uncap it, there is often a large amount of ink in the cap and covering the grip and the nib. As soon as I uncap it, my fingers immediately get stained and there is ink dripping down the barrel of the pen and all over the place.

I am unsure as to which route exactly the ink is leaking out via. To me it seems like the plastic section that holds the nib and the feed (and seems to just friction fit into the barrel) has become loose, and has a lot of movement within the barrel, and that potentially ink is leaking down the sides of this. It's hard to confirm exactly.

I wondered if anyone else has experienced this with a Lilliput, and if so, is there a fix? Or something I am doing wrong?

My previous pocket pen was a Kaweco Sport, and I never had any similar issue with it.

Any thoughts? I love this pen and want to continue using it for this purpose, but it is getting too annoying having to deal with these kinds of severe leaks every so often.