Gareth, Are you sure it requires 3-4 Bar; that's 45 - 60 psi! If you blow the gas flow against your hand (no wire) you should just feel a gentle draft; not a blowing gale.
Jake SS has suggested a good way to check for leaks; without touching the torch switch (or indeed even having the machine switched on), turn on the cylinder valve for a couple of seconds then off again. Wait 30 seconds, turn on the machine and listen to the torch, you should hear a 'puff' of argon just as you press the gun switch. If you do, then the machine and regulator is fine, if not you have a leak.
Jake SS has suggested a good way to check for leaks; without touching the torch switch (or indeed even having the machine switched on), turn on the cylinder valve for a couple of seconds then off again. Wait 30 seconds, turn on the machine and listen to the torch, you should hear a 'puff' of argon just as you press the gun switch. If you do, then the machine and regulator is fine, if not you have a leak.