On the metering unit mate, just above where the air filter starts coming out, theres a small screw flat head type, undo that, then insert a small allen key, think its a 3 or 4 ml,push down a bit and turn it clockwise a small amount (better check its clockwise though 95 % sure),.

I would do this on a CO machine though, as its really senistive when u turn it.
Mines set at 3.5% and ran fine and dont lean out. But mines modded.