OK, I called Marineland (United Pet Group) at 1-800-322-1266. The woman I spoke with was very helpful, and she actually owns the same model filter I own (C-360 Marineland). I explained that I already used the silicon lubricant on the o-rings, etc... First off, she said priming the filter should be VERY easy. I explained that I normally need to pump it what feels like hundreds of times over a period of 10 minutes or more just go get it going. She believes the primer pump is leaking air, and that this is the reason so much air is coming out of the filter and it is so noisy. Since they replaced my first filter a year ago, this one is still considered under warranty, so they are replacing it. I am sending them the filter head and the valve block, and they will send me a whole new filter.
I must say, the experience is frustrating, however, the customer service is very good and I am glad to see they stand behind their product and don't give much of a runaround.