If I have to take a guess I'd think the first letter would be a P, B, R or D. After that some vowel and then the S you mentioned.
I agree, E and F could also be possible as first letter.
Because the rank of sergeant was essentially reserved for peacetime recruits who had signed up for several years (known as ‘Kapitulante’), up to a maximum of 12 years, after which they were generally promoted to Vizefeldwebel or Vizewachtmeister and very often left the army to take up a civil service post (in the police, customs, etc.).
In this case, it is also highly likely that this helmet either did not see action – if it remained in the possession of the soldier upon his return to civilian life – or that it ceased to be the soldier’s property once he left the army prior to mobilisation (the helmet is dated 1900 and a 12-year-old Kapitulant would have left the army in 1912–13) and it was returned to the Kammer for distribution to another Unteroffizier Portepee upon mobilisation in August 1914 (in a manner of speaking, a reallocation, as the name tag had been torn off – much like my example above of Robert Reinberg, who was wounded in September 1914 and whose helmet was reallocated to another recruit).
It is always important, if possible, to know the circumstances in which the helmet was found, because there are unwritten rules, established on the basis of numerous confirmed observations drawing parallels between a soldier’s rank, his period of service and the circumstances and locations in which the helmets were found . Either in Germany, in the family of the former wearer, or from a French, Belgian or English family whose ancestor may have brought the helmet back as a trophy. In the case of finds in the USA or Canada, these are very often souvenirs brought back after 1945 by GIs, also from the German family of the former wearer, as German families were suffering from famine at that time and had sold many personal belongings to buy food and simply to survive.
I have helmets in my collection that meet these three different criteria.
Philippe