I was refering to the bottom picture of your aditional pictures
normaly if it has the spine on the helmet there should be two holes one inside the haube like on pic 1 and one near the square screw
if one sweats a lot the can lower the litte lid on the spine for cooling there brains
i do have a similar helmet like yours and it has the same issue
could be happened during assembly or anything or having strenghten these fragile helmets with spare parts
the last line is just my wild guess don't take that one completely seriously
if all the parts of your helmet are green then the eagle also has to be the same colour
otherwise there has been a switch over the years
you can find these plates but that is very hard to resemble the same colours
has your helmet a faint stamp inside that sounds like the one below
BAX = bekleidungsambt 10
f =feldbrauchbar
if it has an f in it ,that's because it was sent back in to a repair unit and after being repaired the soldier
could ware it back in the field
greetings
jonas