slide a thin strip of metal such as a feeler gauge or sheet metal strip between the rail and the drawer. there is more than likely a small tab on the drawer that catches on the slide and you need to slip it past a catch on the rail.
as sk stated.
there's a spring clip in the drawer slide.
rustoleum makes hammered paint.
a quick resto i did on a huot box a few years back. now, it's kinda buried. too much **** to move, to drag it out for a better pic
These photos were recently posted in another thread... hope it helps.
Once you get 1 drawer out it will make more sense. I have used a bent 4d finish nail too.