Nancy,
I already have a replacement slide plate on the 66-1. I keep extras on hand just for that purpose. Eventually I'd like to find an original with the patent dates, but for now we're good to go.
I've done two quilt covers with two of my 66-4s, they do indeed sew very well. Last night after a good drink of Tri-Flow I threaded the old gal up and tried her out by turning the hand wheel by hand. Very nice stitches for a 99 year old machine.
I'm in the middle of two quilts, one for each of my Aunts, that I'm sewing with my mothers HOTHER. AFter that we're gonna make us one and I'll be trying my 66s out for sure.
There is a couple Singer machines that are lumped together under a model series. I believe the 6010 and 6020 is one of those and that the only difference is the number of built in stitches they have. But, don't quote me on that.
Joe