Possible causes are a leaking piston, hairline cracks in the grip section, pressure differences (aircraft, shocks) or simply ink residues in the cap — simply flushing and drying cap and feed often already eliminates the problem. In the concrete case, a hairline crack lay in the nib carrier between nib edge and thread; such cracks arise from the tension with which nib and feed sit in the ring. Own repair (gluing) is possible but risky, since on disassembly lamellae on the feed can break or the nib can be bent. Recommended is the factory repair at Montblanc; alternative contacts are Maxpens, Interpens or Penboard. According to collectors, a comprehensive factory repair (incl. barrel, cap, clip, cap top) cost only around 61 euros.