AD541546, AD-541546 and ad 541546 are treated as the same number.
A model-only search finds catalogue records and manuals. It does not date an individual machine.
Select a family only when it matches the machine’s model label. A similar-looking serial can use a different numbering system.
Later rules come from a technician’s transcription of service documentation. A single year digit cannot establish a decade. The 2001 has more than one system.
Full Singer lookup & label guide · Manuals+