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However, to see the keyless work requires the dial to be removed, which may not be possible, and many older movements are not documented in these references.
The pictures on this page can help to identify movements without seeing the keyless work, but be careful to make sure that all the features, the shapes of the plates and bridges, the placement of the screws and pivots, are exactly the same; similar is not close enough!
If you click on the pictures a bigger one should pop up in a new window.
These are smaller, simpler, and less easy to identify with certainty.
The setting lever spring was an evolution of the earlier simple cover plate that simply kept all of the parts of the keyless work in place.
To see a clear example of this look at the section below about Eterna movements customised for Stauffer & Co.
Compare the bridge shapes shown in Jobin for the Eterna movements and those seen on Stauffer branded Eterna movements.
Note that the setting lever screw is an exception to the rule about screw placement, it can be in different places in stem set and pin set varieties of the same movement, or absent altogether if the keyless work is negative set.