Adjustment screws as in plural ?, I think you must be reffering to the fuel injection head, has a screw next to each pipe going to the engine, these are for fine adjustement, don't touch, only ever used in calibration.
The screw for co adjustement is in a silver tube that sticks up beside the rubber trunk cover bit that joins the fuel injection head onto the air filter, sometimes has a small cap covering it.
This takes a 3 or 4mm allen key, long one down the tube about 4-5", then turn, don't press down as this will affect the reading.
If you're unsure pm me your email addy and I'll send a clear piccie for you.
tabetha