There is a lever that it appears would push up the bobbin. And, regarding your earlier post, I did find what you mentioned, that the 66-8 has the stitch length lever, and mine has the knob. So, best guess is a 66-6, based on the basic tension, the stitch length knob, and the non-slotted balance wheel. Which then points to the "early" bobbin winder. I found one on eBay that seems to match visually, and per the description requires a belt slot diameter on the wheel of 3 1/2 inches, which is what mine measures. This is my first venture on repairing/restoring anything, and my first taste of what it takes to identify really old things and their parts, and then find replacements. Hopefully, it will get easier. Thanks!