All it takes to free up a rusty all metal machine is oil or solvent and sometimes HEAT. I have found that if oil can't seep into the seized up joint it can't free it up either. That's where the heat comes in. The heat causes the metals to expand and then the oil or solvent can get between the pieces and work. That's what I did yesterday with the torch. I would not have done that on a machine with plastic parts, but this one doesn't have any and I didn't concentrate the heat on any one part. I didn't even damage the paint.
Once it's cleaned I'll have to retime the hook and needle bar, but I think I can do that.
Joe