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Are they treadle machines or electric ??
The first one may be just a parts machine !! Looks like it may be missing a few pieces !! But if the other two are in reasonable working order,,even though you may need to replace the belts,I think its a good deal !! Many people now are looking for good working treadle machines and I think Singer still makes all the belts ect !! I learned to sew on an old Singer machine quite similar to those !! Made a fine stitch !! Just watch your fingers,, I accidently sewed mine to a dolls dress !! Not fun !!