@Paularhion @penfount (It’s not clear to me if this post will reach your notifications on lemmy, but I’ll give it a shot) aside from replacing the converter, you can try dabbing silicone grease on the screw threads where the section attaches to the barrel. This is how pens are waterproofed for eyedropper filling. It’s not expensive; fountain pen shops sometimes stock it but so do other crafts supply places.

@Paularhion Without more photos it's hard to say but to me it looks like the converter isn't seated fully or it leaked around where the converter meets the section.My only FPR pens are piston fillers (Jaipur v2) and eyedropper (Muft) so I am not terribly familiar with their converters.Maybe a little silicon grease around the tip of the converter might help it seal there if that is what happened.Heat setting the nib+feed may also help if it isn't back far enough. FPR has videos for that.

@Paularhion Is there ink behind the piston of the converter? If so, replace or, maybe, try greasing the piston.

(looking at bottom half of picture) that sure is a long weed pen.

(looking at top half of picture) Oh.