I have a set of hollow ground gunsmithing screwdrivers. These are great for removing jets. Better than grinding the edges off a standard screwdriver. If the jet is really stuck i soak it a day or 2 with Seafoam Deep Creep.
While you are buying screwdrivers consider a set of JIS screwdrivers. Contrary to popular belief most cross slot screws on mowers are JIS and not phillips. Those real tight bowl screws just don't fit a #2 phillips but a JIS driver fits perfect