Most of the atomisers made in china use metric grub screws in either M2.5 or M3 (thats 2.5mm wide or 3mm wide by whatever depth they are) you need to measure them (accurately) and buy the stainless steel equivalents. eBay has sellers that do them and they are usually £2 to £3 for 20 or 50 of them. if they are cross-head or flat head screws they can be a little harder to find suitable replacements but not impossible. Do some measuring and googling and all will be well.
Hope thats useful