hey, the air regulator knob on my husky h1820f came loose. when it is turned, it doesn't adjust the outlet pressure and just spins freely. Also, the knob seems to be separated from the back piece, which is what actually screws on the thread. Any idea what the problem is or how i can fix it? The picture included is what the knob looks like (not mine), the separation that i'm talking about is shown between the two red pieces. Thanks.