I picked up an eBay 149 at a parts pen price. I thought i saw a nice xf nib through the fuzz of the pictures. As expected it came with undisclosed problems. In this case, it was that the helical rod has separated from the piston knob. Is there a fix for this aside from replacing the knob and helical rod as a unit? Here are some pictures:

https://imgur.com/a/gJZJYh8