If you care about setting your serial number back to 1870, you can run
the command:
??? SERSET 1870
via either the GPIB port or the EXECUTE TITLE facility.
In the service manual, the command:
? FACTSET 11023,1
sets the analyzer to a C series.? You could try "FACTSET 11023,0" to
see if it will put it back to an E series.? Just a guess.
-mark
