I would do it for my own nib.
But honestly, the time, effort and cost for me or someone to clean the nib and mail it back to you would not be worth it.
Follow along and you will see why I say that.
And maybe you can do it yourself.
Use an ammonia solution of 10 parts water : 1 part ammonia.
Run the ultrasonic cleaner (USC) for about 2 minutes, and watch to see if any ink comes out of the nib.
Then run it again up to 5 more times, each time checking the nib.
Although given what you said, I might just skip this step as it sounds like you did it.
If the ultrasonic cleaner does not do the job, the next step that I would do is potentially damaging.
I would take the nib assembly apart, then inspect and clean the feed without the nib in the way.
The danger here is taking the nib assembly apart. The collar could be damaged or broken during the process. It depends on how flexible the collar is. A brittle collar could break when the feed is punched out or the nib pulled out. And of course you do not want to damage the nib during the punch out. To do this:
- You need the following tools:
- - a spare section, or the section from your pen w/o the ink sack, to hold the nib assembly.
- - a punch out block or similar to support the section and allow you to punch out the feed w/o damaging the nib.
- - a punch and hammer, which you may have in your general tool box.
- The basic steps are: install the nib assembly in the section, put the section on the punch out block, put the punch onto the back of the feed, tap the punch with the hammer.
- An alternative is to heat the collar, and carefully try to wiggle the nib out. If the collar if brittle, you could break the collar.
If the collar is pinned, it is more difficult to take the nib assembly apart, as you first need to get that pin out. While I have seen these pinned nibs, I have not had to disassemble one.
If someone used India ink or similar non-fountain pen ink in the pen, the feed might or might not be salvageable. It all depends on being able to disolve or scrape the feed channels clean. BTW, I have an Esterbrook 444 dipless inkwell where it appears that the prior user did use india ink in the inkwell, as the STUFF in the ink well did NOT disolve with water at all. I had to physically scrape and chip it out.
To return the 9xxx nib to you, I think the cost of a padded envelope is about $1, and postage for a padded envelope is about $2.40. Total $3.40
If you give up, I would be glad to take the nibs and give it a go.