Sorry...yes "83"
100% this is related to the aircraft werk number.
it was common practice to write either the full werk, or the partial werk on the inside of inspection hatches. This was in-case the hatch was removed fully during maintenance.
Though it was not common on Messerschmitt-built aircraft, it was common practice by Junkers and Heinkel.
That said...it "could" be in reference to the specific part number. For example, a Focke-Wulf wreck that was discovered last year had a "13" written on the inside of the left side leading edge wing MG cover. The only correlation that had, was that the full Fw190 part number of that specific hatch, ended with a "13".
If there was an He219 parts list around, one could verify to see if both of these hatches had a part number that ended in an 83.
That would then bring us back to the other number that was written..."253". Which leads us nowhere...
Any thoughts on the "X14"? Originally written in heavy black paint, it seems to be quite important...especially on the outside of the hatch...
Mike