I have a Potter proof press No. 2. The badge says A. F. Wanner & Co, not Hacker, so maybe an early one. I want to add it to the census but can’t be certain what the serial number is. Below the badge is a small number plate that says PE20. That seems like a strange serial number – what could the PE mean? There is also a number on the end of the gear track that says “No. 667”. Could this be the serial number?