Citizen’s second generation Jet movements, the 41xx series, were launched in 1964 and were used in the ‘Seven’ auto dater models. They were made with 19, 25 or 35 jewels and a ‘Monthly’ model was part of the line-up, but they were soon superseded by the newer models using swinging weight movements. NB: There is also a ‘7’ in the ‘SM’ line-up, but this used the 23 jewel 4600 movement, one of the first of the swinging (also known as oscillating) weight rotors – so it doesn’t have a Jet rotor.
This week’s example is one of the 25 jewel variants which uses the 4101 movement (see the Jet Automatic page for more detail on the movements used – https://sweep-hand.org/the-jet-automatic/). The dial has the applied ‘7’ logo, not found on the earlier 03/11xx models:
Typically marked ‘Parawater 40m’ the Sevens all feature separate date and day windows, and I believe they all have a date quick set mechanism, known as Easy Change (EC). This is activated by repeatedly pulling the crown out to its last step and then pushing it back in. The day is set by winding back and forth past midnight then back to around the 8 o’clock marker.
The font used is distinctive, whilst the stylised Jet motif has been dropped:
This model has a one-piece case, with typical markings on the back, showing production in November 1965. The case number is the older type (ADSS81302Y) and the case back sticker is still in place:
The same font and ‘7’ logo are used on the back:
For more information on the Monthly model see this post, where it is shown after its successor model: https://sweep-hand.org/2011/05/20/this-weeks-featured-watch-4-the-monthly/