the damaged part of the buttstock was not to remove a serial number. the Russians and Yugoslavians stamped it on the left side, and the Belgians painted it on the left side. the Germans never put it there, only under the stock or in the barrel channel.
but yes, the sight hood is not original to it nor is the cleaning rod. the rod it has now looks to be a 10" cleaning rod and it should have a 12" cleaning rod.