I found an old hand drill at a garage sale recently. The mechanism was stiff, there was some
rust, and much of the paint was gone:

I took it apart. The jaws did not want to come out of the chuck, so I left them there. They seemed to be working OK.

I used Naval Jelly to remove the rust from the metal parts. The active ingredient in it is phosphoric acid, which is stronger than the acetic acid of vinegar which I have used on previous occasions. I am escalating :-)> Afterward I rinsed off the Naval Jelly, dried all the metal parts, and liberally covered them with WD-40.

The wooden handle on the crank was loose. I gave it a couple whacks with a hammer to tighten it.

I repainted the big red gear. I lightly sanded all the wooden parts and then gave them a good coat of boiled linseed oil. After all that dried I put the drill back together.

It works and looks much better now. The mechanism is easy and smooth.