Question about old 6F-A powerfeed

I recently acquired a 1948 Bridgeport. This is my first mill. I know the round ram and M-head are not seen as ideal by many, but I'm just a hobbyist and I think it will more than meet my needs. The prior owner drilled into the table in a few places, and it needs paint, but internally it was in good shape other than having decades of caked-on grease. I have torn the whole thing down, cleaned, reassembled, and lubricated.

The powerfeed is an old 6F-A model (which I learned from another post here). It was full of grime, so I washed it thoroughly with diesel fuel. The gear teeth were in great shape underneath it all. I reassembled it and filled the gearbox with automotive gear oil, and it works great! Problem, is the gear oil drips out slowly (a drop a minute or so) and drains completely in a matter of about 2 days (and makes a huge mess).

My questions are:

(1) Is the unit supposed to be full of oil? I don't see any other way that the top gears could stay lubricated.
(2) How do I keep it from leaking? There is a oil fill area that is near the bottom of the unit, and oil will leak out if the level is above that point.
(3) Am I missing something else important? I'm totally new to this.

I appreciate any advise y'all have.

Cory