Are a missing 925 stamp and a "W-Germany" inscription without serial number in the clip plausible on a Montblanc Solitaire with brass body and silver corn guilloche?

This constellation is plausible: writing instruments with brass body and silver corn guilloche bear no 925 stamp, and the inscription "W. Germany" points to a production before reunification 1989. Serial numbers were standard-introduced at Montblanc only after the fall of the Wall, which is why their absence is normal on these pieces. To what extent remaining stock of "W. Germany" clips was still fitted after 1990 is not finally clarified. With a consistent description, proper photos and a reliable seller, from a collector's view little speaks against the purchase.