As you might have seen, I recently picked up a pair of vintage Japanese eyedropper fill pens. Both feature an ink shutoff system that uses a blind cap and a shaft that runs through the barrel/ink chamber. At first, both seemed to have an adequate seal for daily use (after I removed all of the solidified grease from the shafts and replaced it with tacky silicone dive grease), but after a couple of days inked, they have both leaked ink into the blind cap... the larger pen looks like the shaft is threaded into the blind cap on reverse threads, but they won't budge with safe amounts of force. The smaller one isn't giving up any secrets

I have seen (and own at least one) Japanese pens of this type, that have a threaded retaining ring, beneath which a cork seal acts as a packing unit for the shaft, however those pens were likely older pre-war models and both of my "new" pens seem to use some sort of different method, as the seals appear to be under permanently attached parts of the pen. If any of you have suggestions as to the assembly of these seal units, or know of any pen repair businesses that have experience with vintage Japanese pens, that information would be greatly appreciated!

Some people cut off the shaft on this type of pen, then permanently seal off the bottom of the barrel so that the pen can at least be used as a conventional ED filler, but I'd rather not do that If it can be avoided.