You would think the rubber material around the bearings would seal those areas, but maybe they don't conform correctly causing an air leak. Did you put sealant on the mating surface around the cylinder base.
My poulan/husqvarna parts distributor shows the 530047077 as the superceded part number. And you need to order it since my distributor also shows it as NLA
I got thinking that that hex part that is sitting inside the fan is supposed to be one piece with the fan not two separate pieces.
This should be a similar carb as what you are using.
In the second picture of the link of the carb that I posted the nipple on the top...
My experience has been sometimes you can move the motor by hand and other times you can't, but can see it move when the mower engine is shut off. Sometimes 1/16 of a turn is all the motor mount bolts will turn when they are loose.
I have a customer with a Snapper that will have issues with...
Possibly have the fuel lines reversed where they are connected to the carb. the fuel line with the fuel filter should connect to the nipple closest to the side of the with the cover with single screw which would be the fuel pump side(nipple on right side of carb as mounted if I remember...
Loose motor mount bolts will normally show up when starting and stopping the engine. just the slow turning off balance clunk clunk sound. If the only time it does it is when the deck is engaged then I would agree with Bert about a deck issue.