Of course the sac was toast. When I pulled the nib section the pressure bar fell on the table. There was no spring or spring parts. After close eximation it dawned on me how the thing was ment to be assembled. The last time the sac had been replaced, it appears the pressure bar had been put in upside down and 'off the track'. My best guess is it was glued to the sac so it would stay in place.
The best description I can come up with for the pressure bar is it has a "C" section with the open part of the "C" to the lever side. There is an end that fits into the "C" on the lever. It was also bent and showed a wear spot from the lever on the side the sac should have been.
It took some cleaning, bending and reshaping before I was read to stuff the pressure bar back in and mate the lever bar end into the slot of the pressure bar. And, it might go either way ... but, further examination shows only one way could be right.
On one of the many 'stabs', I finally got it right. The pressure bar worked. Clearance says it will take a #12 sac. The sac is installed and left for the shellac to set. The pen is assembled.

Writing sample:

Fun Pen!
Ron
edit cuz aikin ain't spelt ailin