I would really appreciate if you can scan your owner manual.
As the serial number is concerned, I will try to explain you what I see. Beware, I'm not an English-speaking person so my description may be hard to understand.
The two front forks are fixed to a pivot thru two triangles (Maybe these triangles are the fork plates?). Here's what is engraved on the pivot:
DGM. 12440. OM
The moped was brought from Italy by the owner in the seventies. He told me that the moped was not new at this time and may be way older.