Montblanc's service department no longer holds spare parts for writing instruments of the 1970s such as the 1266. Sending one off to Hamburg in such cases usually means getting it back unrepaired, so the cost, the waiting time and, where it is shipped from abroad, the risk of losing it altogether can all be saved.
These models can be repaired nonetheless, because the mechanism and the section are the same as those of the plain black Montblancs of the same years. Anyone able to lay hands on a suitable donor pen has the necessary parts in front of him. That is precisely the speciality of the independent workshops and dealers in old Montblancs, who keep stocks of such parts and will fit them.
It therefore makes sense to look for a workshop within reach rather than send the pen halfway round the world. In Japan, Eizo Fuji in Tokyo is a well-known address for Montblanc models of the 1970s; in Germany several workshops specialising in vintage pens take on work of this kind. Before placing an order it is worth weighing the outlay against the value, since the plain production models of those years are not high-priced collectors' pieces.