Hi Eliot, thanks for the kind welcome 
I havenât thought about putting the sea-view penetrator partly off of the table with the red penetrators on the table. I will be sure to try that!
When I said, âhow difficult is it supposed to be to put on the second o-ring?â I should I said, âHow difficult is it supposed to be to put the flange with both o-ringsâ. I was able to get both o-rings onto the flange using the o-ring tool. I was also able to put the flange partially in the tube, but only up to one o-ring. The o-ring closest to the endplate is the o-ring that is preventing me from putting the flange all the way into the tube. My problem is similar to this forum post, except I have a larger diameter flange and tube (O-ring Flange Installation).