Either with diagnostic equipment or checking your setting.
FYI, a member of the regulation authority for this stuff plays airsoft with us and uses the high power radios too. Its not a big deal. 4W wont go very far.
As log as you keep it on the proper frequencies there are no issues.
If you need it quickly and cant wait for a restock in country, http://www.409shop.com/409shop_product.php?id=110128
I know a lot of guys who have ordered through them, service is great.
Pickup a spare battery for the radio too if you ever plan on playing 24hr games.