It seems like you could drop in a replacement presser bar pretty easily on the 66. As I recall there was a screw-in bushing and tension spring on top that just backed out, a sort of a bar just behind the face plate with a little cheese-headed screw that your machine screwdriver ought to have no trouble with, and you would pull all of the business off the business end so it pulls up and out. The machines after the 66-1 had a side clamp, and all you had to do was scrounge a presser bar off of one that was already shot for sewing, because the presser bar wasn't a high-failure item you could always lay hold of a good one. If I had a 66 here I would show you with photos. Cheers! Chaz