[Electronic M]

If it is a ferrite core on a transformer you are adjusting you should use a non-metalic screwdriver.... metallic screwdrivers (in addition to being hard and having the potential to crack the core or the slot off the core) have magnetic effect on the core similar to the slug...so if you get something adjusted dead on it will stop being dead on as soon as you remove the screwdriver....the effect even happens with non-ferrous metal screw drivers. Copper and aluminum drivers change the inductance tuning in the opposite direction of ferrous ones (this can be used to ones advantage if a coil needs to be adjusted by knifting or has a stuck slug or other issue that makes you not want to adjust it more than once).

If you don't have a plastic screwdriver and don't want to wait on mail you could do what I used to do as a broke college student...take a defunct mechanical pencil (I think I used the bic ones with the clear outter barrel and black inner Barrell), pry off the stiff plastic pocket catch file or grind the end down to the blade size you need then super glue the other end of the catch into the inner barrel of the pencil to get a long handle (I still have 1 or 2 I made floating around here somewhere)...I also used to file down the weird alignment tool like plastic sticks that come with newer Weller soldering irons, but those didn't seem to turn out as well.