Well, to add to the discussion, I have a Pelikan 600 pen, which I started to use with Noodler's ink and other brands. The problem with the pen is that the pen is too wet if you use non Pelikan brands of ink. It is wet as a sea, and even a fine nib line dries out like a broad one. After one or two ink changes, I finally purchased two bottles of Pelikan 400 ink and the pen started to write very well with the ink. Seeing that the problem was the same for a Parker Duofold Centennial, I tested the Pelikan ink with the Parker, and the pen ceased to be wet. For any other pen I use the Noodler's black because it has proved to be the one that I can easily use because I am a left handed writer. Noodler's ink has the advantage of being very strong in the paper, and in some hours it becomes indestructible, water cannot smudge it. I also use my pens to draw. Noodler's is very good for that. Another brand I like is Shaeffer ink, it is very dark and it also dries very strong. I think that no pen can be indestructible, and any ink that comes for a fountain pen can be good, and this is a matter of much debate among fountain pen users. At times I also purchase many other brands of ink, to test them. Whatever we are saying here adds to the liberty of making a decision to purchase the ink we want. I don't think that it is an absolute thing that a pen should use that particular brand of ink. Period.
I have a Pelikan 600 with a broad nib and used Noodler's ink without any problem. Diamine ink too.
Maybe you need a new nib?
Pelikan nibs simply unscrew and you can buy new nibs online.