Always use the proper ink. Fountain pen inks can clog technical pens.
The points are generally made of stainless steel, tungsten carbide, brass and plastic.
Non-technical pen inks contain chemicals that may be corrosive to these materials.
The ink must be fresh.
If the ink looks gray or has floating particles, it has deteriorated and should be discarded.
If the pigments in the ink have "fallen out of suspension" shaking will only produce air bubbles.
Mixing inks or adding water or thinners will also deteriorate the ink.
Never disassemble the point portion of your technical pen, since the tiny filament wire can be easily damaged.
When ink dries, it undergoes a transformation in its chemical composition, and cannot be "reconstituted" with water.
The only way to clean a technical pen that has dried out is with an ultrasonic cleaning machine, which actually vibrates the particles loose. It is extremely important to clean your pens if they aren't going to be used for more than a day or two.
Otherwise, the filament wire can get stuck in the dried ink and break off!
If this happens, the point is ruined, since the filament wire cannot be replaced.