Is it meant to be 3mm on all metering units?, as everyone who is selling them seems to either not know where it is, or dont have a 3mm adjuster but a flat head screw or torque bit or some other random adjuster

I always thought it was 3mm as my one that has just packed up has a 3mm adjustment, if u lot could tell me whats on yours it would be gratefully appreciated

Many thanks Statey