The 65xxxx indicates the year, the lens serial should be the same or one out eg 64xxxx.
They like the Contax II or IIa are slow to wind on.
I have a collection of them and after I refurb one it is reliable. They will snap a ribbon with a lotta use and frame spacing is not wonderful, the Contax II is the same and also needs a refurb.
They are easy to strip but people sometimes send me one (or two) in a zip lock bag of bits. Spares are plentiful as there is a cottage industry converting their mount to a Nikon to Leica adapter.
The 35mm, 85mm and 135mm are ok lenses and cheap. The 28mm is also good but rare, the accessory finder covers all the focal lengths and is cheap.
The J8 needs a hood available from China.
They did a modern design double Gauss 5cm on later models better edge IQ at /2.