Ever $ince I replaced the screws in my handlebar reservoirs with OEM ones from
HDL back when I got my bike, they've remained in good shape, just use the
right screwdriver...
I finally hosed up the head on one of the screws in the rear brake reservoir the
other day though... near the end of the day, it was getting dark, maybe the
"phillips" cross had dirt in it, ida know, anyhow, I needed more.
The next day I headed out to the local places that have drawers full of Hillman
screws. Lowes: zilch. Ace: handlebar reservoir screws (55 cents each). Tractor
Supply: rear brake reservoir screws in 3-packs: about a buck fifty.
All in stainless...

You can see the metric size and thread pitch on the package...

-Mike