Thanks to all of you. I will have pictures posted once I get the helmet. The seller (a lady who wrote that her father, then a US soldier, brought it back from Germany in 1945; it was always in the family since then and she was "shocked" when she saw the price the hat had fetched...) sent many additional pictures, all of them confirming the great and genuine condition of the helmet. The spike may have been undone at some point, though, and put back in the wrong position. No big deal. This is very frequent. It was also the case on the Saxe-Weimar reserve helmet I purchased some time ago. I just fixed that yesterday.
Bruno