Lock nut stuck on this Gold Bond branded Wahl Eversharp Doric

[Siphonophore]

Hello all,

I've recently joined, just lurking and appreciating the fountain pens on this forum.

The problem in this repair of this Wahl-Eversharp Doric, branded as Gold Bond, is that the lock nut is stuck near at the end of this threaded portion of the rod. The nut was hacked a bit because I couldn't get a good grip with my needle nose pliers, so I'm sorry for that. I was trying to use petroleum jelly to lubricate the area, but the lock nut is still stuck on the rod. I've thought about using some WD-40 on the area as well as using a vise grip on the nut, but it's important to exercise caution so I haven't continued the repair.

Do you all have an idea what I should do next? I've attached a photo, hopefully you all can see it well.