While everything seems to (still) work, inside the Copal 602 clock I found a loose palette. It has one hook missing, and it should be possible to rebuild it with a tiny cut of hard plastic of the proper thickness. I still have to figure out how to keep it in place while the superglue does it job.
But, what if it doesn't work? (Or I get it totally wrong.) I think modern technology can come to the rescue: laser cut. Probably the hardest part to find is the right plastic (let alone the color), then with a 1200 dpi scan of an original palette and a digital ruler on the picture, a digital model can be drawn. Finally it is a matter of few seconds under the laser.
Here is the 1200 dpi scan if anyone needs it.