Original nib keys Montblanc gives only to its own service centres; some collectors have therefore built their own tools; instructions and special tools can be found on sites like penboard.de. Important: Montblanc uses no self-sealing threads like Aurora or Pelikan but a silicone seal that on disassembly must absolutely be renewed; otherwise the pen leaks. Hardware-store silicone is unsuitable, since not sufficiently elastic and ink-resistant; high-quality, ink-resistant silicone is needed. The nib unit can be unscrewed counter-clockwise at the front matt-black ring of the section. Because of the risk of permanently damaging a Montblanc, experienced collectors advise on valuable pieces repair by Montblanc or specialists.