Before you buy a new water gun,you should always pressurize it and see if air shhots out. If it does buy it if you like it,if it does not it could be defective.
When you buy a new weapon make sure all gadgets on it work.
in the case of this monster you should
A) make sure it pressurizes and fires
B)When it is filled up make sure the pressure gauge works
C) Check for leaks
D) Enjoy you gun
When done always leave it out to dry or mold may grow in your new weapon