Lead screw end support bearing

After I've taken out the lead screw, I found that, the end which close to the headstock was directly inserted into a tube.

Without any bushing or bearing support, I can see there has a scrap mark on the inner surface of the tube. And it was definitely a thread scrapped mark!

Luckily, I find a 12x8mm bearing on hand, and...
Turn the lead screw end down to 8mm and bore up the tube to 12mm...

And that's it, you can use what ever spec. of bearing , as long as it is not larger than the tube (0.625 inch), cheap and easy to find for you.