Quill feed issue

I am new here but have been reading post off and on for several years now, and I have learned a lot, so I figured I would join.

Having said all that, I have a question. I have a step pulley J head Bridgeport mill that has a quill feed issue.
Here is the issue, when I engage the auto quill feed engagement, the feed reverse does not turn at all. Not only does it not turn but you can not push or pull it out (this is the case even if the auto quill feed engaged or not).
The feed engagement lever will engage and hold itself in but the quill does not move.

I have read a bunch on this site as well as other places but have not seen this exact problem. Can someone point me in the right direction on this, and if the head as to be torn down, how far down will the head have to be torn down to fix it?

Thanks
John

Oh I am guessing that this is a mid to late 70's head, but how do you get the date on these?