Compact Threaded Deck Mount Install

I just bought a couple of these and I tried screwing the nut on the post just for giggles and I found it to be VERY hard to thread it all the way up. Anybody else have this problem and what did you do about it? The instructions say to use a sealant on the flange (obvious) and the threads of the nut, did you put goop on the threads of the nut? I thought goop may make it easier to thread the nut on but I don't know, never used it before.

Any help would be greatly appreciated.

Yeah, I found them a bit on the tight side. I just used channel locks to work them up to the top.  Gooped the top down to the deck.

Great, thanks for your help.