Excavating (or destroying?) a layer of history on a machine

This particular Underwood 5 was bought locally, originally meant as a reference machine to help with the restoration of an older 1920 Underwood 5.

This machine was not only a newer 1928 version, it also showed evidence that it was refurbished and put to use in a later, very specific time-period in the British Isles. In archeological terms; it had acquired a 'layer of deposits'.

Taken off the machine and replaced with 'nicer' specimens. The knobs were replaced with Underwood knobs - albeit later, larger-diameter pattern. The green ruler and especially the wrong-pattern knob on the Underwood were 'jarring'.

The modifications are in principle all reversible; the removed parts are kept. But realistically, this machine viewed as a historical artefact has entered a new phase; 21st century collectable (though not rare). 

Sticking with the 'archeological' viewpoint - this removal of a layer has now, hereby been documented :-)