Do u crack the bottle to clear before fitting the regulator you can be suprised at what can get by the plastic cap on a new bottle we always crack them before putting on regulator
It wouldn't be grease or debris, it's only had 2 gas bottles since new, with a new reg, and I made sure everything was perfectly clean when putting together, it's under warranty for 3 years so I can just take it back to exchange, but just wanted to be 100% sure it was a fault of the machine and not the dodgy reg dumping full bottle pressure in to it that could have damaged it in some way.