2005 Ford F-150 Rattle in transfer case

I am kind of embarrased to tell you this, but here goes. I was having problems with my 4wd trying to kick in while I was driving down the road in two wheel. I did some research and raplaced the vaccum shift solenoid. (Now comes the embarrasing part). I removed the solenoid and put the air compressor in both upper and lower lines to blow them out. When I blew out the lower line I heard a loud pop. Now after replacing the solenoid when I step on it I hear a rattling. When I engage the 4wd and eccelerate it does not rattle. Do you have any idea's?

Thanks Doug