I have a Parker 50 Falcon with a bent nib, and although I gauge the chance of a perfect repair very slim, I will try my best.
The initial problem was the glued in feed. I applied all the reasonable force as I dare, but it didn't budge.
And then I remembered the coefficient of linear thermal expansion!
Approximate numbers are, Stainless 16 X 10-6 and ABS Thermoplastic 73 X 10-6
(meter per meter per degree kelvin)
So cooling it down will make the plastic shrink more than the stainless. Besides that, adhesives generally don't perform well cold.
So I made sure it was completely dry, stuck it is liquid nitrogen for about 30 seconds, felt a small pop, and the nib / section came right off.
I could have tried a regular freezer first, but LN is more fun!
Everything warmed back up with no damage.