I have quite a few parts machines. I have bought machines in bulk. Some times there are parts missing or incredible amounts of rust or other damage or some level of dysfunctional. I keep most parts machines in tact so I can find the parts when I need them to keep another machine going. At least I know where my parts are coming from. Most often slide plates are missing. I do ship parts some times. That 66 you have looks pretty good. I have found I don't like the old refurbished machines where they have been painted over and motorized. I do not like the replacement hand wheels and bobbin winders. They do not exchange back to treadle unless you change out the bobbin winder, too. The ugly 66's and 99's can be very sweet running machines once everything has been freed up. I have one VERY ugly 99 I converted to HC and run a button hole maker on it. Very nice and very handy to keep around. You could keep an extra machine around set up to use a little heavier thread. You have to set the tensions for it. In other words you can set a machine up for a task and if you use it a lot it is very time saving.