The pen described is not a Noblesse but a Montblanc SlimLine, which was produced in large numbers at the time; the collector's value is therefore low. If the nib is stamped "585", it is made of 14-karat gold; otherwise it is only gold-plated. The clip is generally only gold-plated. If ink flow drops with cartridge use, a thorough flushing of the pen with water normally helps. Professional repair is rarely worthwhile on these widespread models, since the cost typically exceeds the replacement value.