There is not such a thing as a BR 18 from the NORD. The (German) seller you mentioned sold a loco which he called a NORD BR 141, which is a wrong classification. BR (Baureihe) was used in Germany, the French called this a NORD 141 TC (http://fulgurex.ch/modelle/n/141tc/141tc.html). It might help to use the right classification.
Regards
Fred