I got it......after reading thr instructions for the forth time I realized
that I had used the inside diameter of the threaded nut. Once switching to the slip ring which is about 1/8" larger I enlarged the hole. Then lubed up the edge of the plastic elbow
with dish soap and it slipped into place. Then erroring on the side of overkill, I put a bead of silicone sealant
around the perimeter of the hole.
Put on the sealing washer and screwed on the nut till the silicone oozed out all around. Should be good to go tomorrow after the silicone is set up.
Cheers from Langkawi, Malaysia