I am just starting out on my machine (an old Riccar) and can't even wind a bobbin. I know I am using the correct bobbin (I watched someone else do this successfully on the same machine, same bobbin).

But now when I try to put the bobbin on the winding post, I can't get it to engage with the notch. It looks like the notch is too far down the winding post - it can't reach the notch on the bobbin to engage it. I tried pushing on it, but that doesn't work. Anyone know what I'm doing wrong?