So in essence if i understand what your saying, I should be using
UPDATE Table
SET Table.FieldNew = (Mid(Table.Field, 1, Instr( ,Table.Field, ",,", 1)+2
(Mid(Table.Field, Instr( ,Table.Field, ",,", 1)+2, Len(Table.Field))
and if that fails i should be using
UPDATE Table
SET Table.FieldNew...