I recently acquired a rather pretty Extra in blue, which leaked a little from the piston knob and clearly needs some TLC.
Following your instructions, Hari, I have successfully taken it apart (hand pressure only: no tools or even hot water needed).
This is what I found inside:
The black stuff caked all over the piston and the inside of the pen is not dried ink; it's crumbly and artificial (plastic, I should think). I'm guessing it's something to do with the remnants of a sealant that is still just about visible on the section threads - any ideas?
My plan is to soak everything in water (happening now) and then carefully scrape off all the gunk from the inside of the pen, the piston and the section/nib before putting it all through the ultrasonic cleaner. I'd prefer to leave the nib in its housing, so won't immediately disassemble it.
Once I've cleaned everything up, I'm wondering about the best way to seal up the the section.
Rick Propas suggests shellac and teflon plumber's tape: that sounds very thorough, but also a little complicated. I'll do it if needed, but maybe there's an easer way that is almost as good. The Good Captain simply used silicone grease, which would be my preferred option if if works long-term. Can anyone share their own experience (and Captain, any thoughts two years later)?