I like Parker Duofolds of all dates, but especially Newhaven Aerometric Duofolds – to write with, that is – not to service. From a repair point of view the Aerometric is a bad design. There was some discussion in one of the pen boards today about how best to go about working on one. If, for instance, a simple nib swap was all that was required, I would pull the nib. This is not something I would normally do. Pulling at thin, flexible nibs can lead to disaster but Duofold nibs tend to be robust.
The process involves soaking (one of the very few occasions I soak anything), warming thoroughly with a heat gun and working the nib from side to side with a gentle pull. It takes time and patience but it invariably works. Parallel pliers can do the job too but I proceed with great caution if I use them. The feeds are fragile. The alternative is to remove the sac protector and the sac, then drift the nib and feed out as you would with any other pen. That seems like an excessive amount of work to carry out a very simple procedure, to me. Sac protectors were not designed to come off and Parker assumed (mostly correctly) that the Pli-Glass sac would last forever and would never need to be reattached. Thus, neither of those procedures is easy. Yes, they can be done but it’s a lot easier not to do them unless you must.
The chap who was looking for assistance bought a perfectly good Danish Aerometric Duofold and found when it arrived that it had a firm EEF nib – something he had not established before purchase and decided he hated. A Duofold nib in that conformation must be quite rare. I’ve never seen one. He wrenched at it and destroyed it because it was as he said, a “nail”, what I would call a normal nib. All of that grieves me. You would think that it would occur to people that it might be an idea to find out at least a little about fountain pen repair before they get stuck in. It would also help to have tools other than a pair of brutal, metal-jawed pliers.