Originally Posted by Mickey2

Singer 431G is probably the only all metal / direct drive motor, and probably the rarest. Vintage Berninas, anything from 500 to 800 series (1950s to 70s) are very much the same machine, with a few differences, size, features, etc, but all basically the same construction. The 1008 is the current of this build. The 800 series and up have more plastic gears than 700 numbers and down. They last though, my 730 is intact after decades of use. I think even some of the 125s had one or two plastic gears, though I actually think the earliest were metal geared. European brands were early to introduce free arm and zigzag, equally so with the plastic gear. Maybe the early Necchi Supernova free arm version is all metal, it's a very nice machine, but if I remember correctly, the Bernina free arm is narrower.