I assemble every BGE that leaves my store. I set the bottom band below the gasket with about a 1/8 of an inch of the green showing, making sure it is even all the way around. I then tighten it down until the bolt just starts to bend. I set the dome on and line it up with the hole for the thermometer centered up with the handle. I just tighten it enough that I can still move the band and dome. I make sure I have a even band all the way around and that my dome lines up with the Base with a 1/8 of inch showing above the gasket. slowly tighten and adjust the dome to meet the base until the bolt bends. I used to check mine with a dollar bill, but have not checked for the last couple years. I have a few customers check them before the bought and were very satisfied with the fit. You always want to re-tighten the bolts after using a couple times.
Never lift the egg by the bands or you will find the BGE in a lot of pieces.
As far as the Daisy wheel falling off always make sure the screw is in the front facing the handle and don't let the dome fly up, hold on to it, helps keep the band in shape also.