Wow, Shooby, did you mug someone and leave a $30 tip?
I bought Mars Staedtler stuff 30 some years ago when I took a commercial art class. I have the compass maker, been in the box all this time. I guess that makes me a hoarder, huh?

I just bought a set (the marsmatic700) at a thrift store here in town for $3.50
So i' understand

I am, at this writing, cleaning a set of these same pens. The dried ink in my pens is the ink that came with the set which has been in storage for nearly 20 years. The pens are cleaning nicely with plain tap water.
Take the whole pen apart including the ink reservoir from the handle, and the little black piece (holds a very thin wire) from inside the nib.
Simply soak in a cup of warm water for a few hours to rehydrate the ink.
Then, hold each of the various parts securely between thumb and forefinger and shake any loose ink chips out.(do this over a sink of water so as not to loose or damage a part if dropped) Keep rinsing and shaking until water is clear. I ended up using a fat bamboo skewer's dull end to vigorously pump some water up and down in the ink well to get the sludge out. Careful with the little wire thing when you put the pen back together - it will eventually find its way back to the center of the nib. Pens have color coded parts so as not to mix it up. If the pen is nice and clean, you will hear the familiar clicking as you shake the pen to start it.

Hey nail polish remover works great on the tip and inside the ink 'tube'. just keep it away from the middle 'body' part because it will melt that kind of plastic.

. This pen cleaning may be helpful. Try it and see.