My Mom had a 306 W cabinet mounted with a knee control... I have that machine now .. and love it..I was never allowed to use "her" machine while living at home.. Me and my siblings had an inhereted Kenmore Rotary.. no zig zag... but did have reverse.
Once in awhile I think my Mom regrets passing that machine on to me , as it still just keeps on going and going. It saw so much use while she had it .. if it was made of cloth she made it.. curtains, coats , slip covers, all of our clothing. I still give it its daily workout.