I am heartsick as I write this post, but wanted to warn others of the danger so they can avoid the disaster I have just suffered. It applies to something at least some repairers do when repairing plunger fillers and replacing the steel rod. If you have no pens like this, you are safe.
To explain, I have to set up the story. I am a writer. Pens are my life. And once I heard of Onoto-the-Pen, I had to have one. Finally, I found one that was unrepaired. It was a nice black 5601 with an amber ink window, probably made not long before World War Two shut down production for a while. This last detail only made the pen that much more precious to me. Before I could use it, I had to have it restored. I will not name any names here, but will say I chose an individual with an excellent reputation. When I got it back, in the fall of 2011, one thing bothered me.
Onotos are plunger fillers. The rod on this one, which had corroded, had been replaced not with stainless steel, as I had hoped, but with some new, high tech black rod which was flexible, unlike a steel rod. Since it did not, when I filled it, look quite like the original, this troubled me. And as I began to use it, I noticed that since the rod was somewhat flexible, it was somewhat hard to "drive home". This seemed a bit dangerous to me, but I got away with it various times, and the person who fixed it was supposed to be an expert. I didn't feel I quite had reason to complain over not getting stainless steel.
Today, I was filling my beloved Onoto. After my cat, and my manuscripts, this pen is the first thing I would grab if there were a fire. Well, some of you will have guessed how this tragedy ends. In fighting with the stupid, high-tech (bleep) which seemed so clever to use - and which needs to be thrust home while the pen is nib down in the ink - a terrible mishap resulted in just what I have always feared, a bent nib. As I am disabled, I will now have to live without this pen until I can save up to get someone to repair the nib AND replace that evil flexible rod with a nice, firm, stainless steel one.
I do not know the name of the black substance which was used, but this is clearly not suitable for the needs of a plunger filler. Having such a rod in place is just waiting for a disaster to happen. In my opinion, any repairer who has been foolhardy enough to use such a material ought to offer to replace it with stainless steel free of charge to all their customers who are stuck with beloved pens which are also disasters waiting to happen. As upset as I am right now - near to tears, to be honest - that may or may not be reasonable, but it is how strongly I feel. In the future, if anyone so much as suggests using such a material in a plunger filler, I will no longer trust that person to work on ANY of my pens.
If it were not for the fact that I am very sure the manufacturer does not market it for this purpose, I would consider suing the maker of the material. However, if they didn't suggest it was suitable for this type of use, then the blame comes down to the "experts" who failed to think it through and realise that even a tiny bit of bending would increase the force needed to thrust the plunger back in, and thus would in time lead to a very bad end.