TS brass acme nut releasing from quill??

Hey all. Picked up a new lathe to play with, a cnc tensilathe. Currently going through it to clean it up and check over everything before putting it to use.
These items are fairly small but these are pretty much the only things that need attention other than cleaning it.

Tried to eject the live center from the TS and noticed a change in turning tension. The quill was loose but the live center was still in there good. The brass acme nut, which I'm assuming was press fit, had popped off of the end of the quill.
It wasn't stripped or anything but it looks like the previous owner drilled a hole into the nut and shank. The hole appears to have threads part of the way down.

Question is, how do I get the acme nut back on and stay on when trying to eject tools from the TS? Do I need a new acme nut that press fits in there better? Do I just get a roll pin or tap the hole better for a set screw or bolt?

Second question is that the 3 jaw Chuck has 2 locking wedges that correspond to a radius on the spindle. I believe this is to prevent back driving of the chuck. One of the two tapped holes has a chunk missing which prevents a secondary hold of the chuck.
What are my options on fixing the back plate?
- Weld, drill, rental
- use one wedge and move on
-drill and tap 2 new holes 90 degrees from current holes

TS nut ;- Loctite and 2 allen grubscrew dutch keys as have stripped out.

Backplate ''move round a bit'' drill and tap 2 fresh holes diametrically opposite each other

Job's a goodun