I don't have a 66 at the moment, the closest I have is a 99K, and a belt driven 201K with a spoked wheel. The bobbin winder is in theory the same, but not spot on your treadle.
If the bobbin wheel presses down on the belt (or the groove in the hand wheel where the belt goes) it's not suppose to have a rubber tyre. If it presses on the metal part next to the belt, it is suppose to have a rubber tire. A black tire looks good on your machine, I think the gray/blue, beige even green came later to suite different finishes.
I'm unfortunately not much help with the treadle details. It looks like there is only one adjustment screw on my machines. With a bit of further investigation and research you will get to the problem. From the picture it looks like the winder can be adjusted a bit lower, but I may be thinking wrong from just looking at the picture.
Last edited by Mickey2; 02-02-2020 at 03:03 PM.