That machine at the top looks like a refurbished machine that wasn't motorized. Can you tell if it has been repainted? Link to thread about refurbished machines
http://www.quiltingboard.com/vintage...s-t277707.html
There are other threads and more info tucked all over the place here. Welcome.
I'm thinking the 128 would be a 3/4 size machine and a 27 would be full sized.
I would also like to see how that hand crank is held on.