Fixing Pilot Metropolitan «leaky» grip issue

Edit: Sadly, the solution described here worked for me for ten days, but then stopped working, and I got leaks again.

I have a green Pilot Metropolitan Retro Pop which is a beautiful beautiful fountain pen (which I have fitted with an extra fine nib yoinked from a Pilot Kakuno, which if you like you a good EF nib, a worthwhile hack in my opinion). It is beautiful enough that for the longest time I tolerated it's one annoying issue: an inky grip.

Yesterday I found a fix. So first, the fix, and then the reason I think it leaks and the solution works.

If your grip gets ink drops near where the nib is and there are no cracks, look at the grip closely. At two sides of it, you will notice lines which you can also feel with touch: they are probably an artefact of the manufacturing process, the seams of the two halves of the grip. Check if they coincide with any part of the nib and feed assembly that gets inky, for example the right and left edges of the nib's root. If yes, gently but firmly rotate the nib and feed assembly so that those seams no longer coincide with any part of the nib and feed assembly that gets inky in normal operation. With my pen, I've rotated it such that, one of the seams rest at something like 20 degrees of angle relative to the nib's surface. In that configuration, the other seam coincides with the opposite back side of the feed in a similar angle, which part of the feed does not get inky.

Now, rub the grip, and the exposed part of the feed and nib with a paper towel, thoroughly to make sure no part of the grip in particular has any ink. Use Q-tips then to thoroly dry the inside of the cap, which likely has accrued some ink from the leakiness. Then cap and uncap the pen a few times, and each time check for ink sizzling out on to the grip like before. If with luck, I explained the fix well and you repeated it accurately, and if there was no other problem causing a leak, like a crack, the issue must be fixed, the grip should cease getting inky.

* * *

So, why does this work, what does it fix? Well, I have no definitive answer, but what I imagine is this: the seams, which are each tiny straight bumps, provide a structure which provokes a weak instance of capillary action—the same process by means of which the fountain pen itself works, tangentially—by means of which a tiny amount of ink travels along the seams, after finding them at the point they (almost?) contact the exposed sides of the feed. Capillary action does not really need an external force to provoke it; it depends surface tension and adhesive forces, as the Wikipedia article says, but I imagine the capping/uncapping action may be contributing to the movement of the ink as well. By rotating the nib and feed assembly, we break the contact of the ink with the seams, so the capillary action cannot start, even assuming the (un)capping catalyse it.