I wouldn't think it does anything, going to empty pins. Maybe it does something on the 500E upwards. Those models have an EQ bypass and a mids EQ switch.
the neck is a 1969 from a bass owned by Dave Short fantastic bassist and fiddle player he removed it and replaced it with a maple neck for a brighter tone. Note the wide fret markers.. they were not available in 1964
I have included this photo because I know that under the white paint is a groove from years of a players thumbnail gouging the wood. the groove has been filled and painted over