What a sad news !
I had in the past some troubles with a helmet without invoice and the French customs didn't want to be comprehensive, waiting for the missing document. The helmet gots back to USA one time and a second time. I really thought the parcel was lost or stolen but ultimately it...
The seller used to put poor quality pictures which does not help to appreciate the way of fixation of the banner. It seems welded.
I asked for better pictures, we will see its answer.
A fake without doubt. The markings for mecklemburg are either GR ou FR. It is a prussian helmet which was changed in a pseudo Mecklemburg. The cocade is modern.
I do not like the marking. Here for comparaison the marking of my JR 88, too from the III/JR88. Sharply different, there are two independants markings for the unit and the Bataillon (and a faded date 1907, between the two).
A picture without the Plate would be interesting.
I wonder that the spike and baseplate could be in iron, not in nickelsilver which should be for a pionnier