Hello. I have recently inherited a Ransomes Fourteen Mark 1 and would be interested to know if its date of manufacture can be determined. The plate on the side of the machine shows it as a Mk 1 with Reg no DF1665. One clue is that I've been told that the metal air filter, which does not have the cylindrical cover with the paper filter, was the standard fitting on early models (see photo) and that it may date from between 1963-5. Is there a way of checking exactly?