Newark Secretary Section, Sac And Pressure Bar Are One

[Bristol24]

I recently purchased a World War II era "Secretary" fountain pen manufactured by the Newark Pen Company. I want to get it writing again but have run into a unique (for me at least) problem. I placed the nib/section portion of the barrel in a 10% ammonia solution in my ultrasonic cleaner. After several minutes, I removed the pen and tried turning and, hopefully, extracting the section. The section turned somewhat easily but I found it impossible to remove. It is not threaded and only moves outward about 1/100" or so, even with significant pull, rocking, and twisting. In turning the section, I noticed that the fill lever had become loose and would sort of flop out a third of the way under its own weight. Holding the lever firmly in place, I rotated the section back to its original position and the lever was again tight with springy resistance. My conclusion: the sac is ossified and completely glued to the pressure bar which is preventing me from removing the section.

 

My question is: How do I remove the section in this situation? I have to confess that I have not tried heat other than hot water under the faucet but I am wondering if heat is going to work. I was thinking about using a syringe to inject a plastic-safe (naphtha?) solvent inside the barrel through the lever slot, perhaps something that would loosen the bond between the sac and section. I would appreciate suggestions