SprueOne, I'm assuming the part you are referring to is either one of the two I highlighted here.
The connector tube didn't cause much trouble. It went together and attached to the side of the frame without much problem.
The horizontal connector, however, posed a little bit of problem connecting to the tube. It has a little key or tab that fits into a notch in the end of the connector tube. The tab and notch weren't really the problem. The end of the tube would start so far into the horizontal connector and then stop. I think the hole in the horizontal connector has a little bit of a taper allowing the tube to only go in so far. I had to trim both parts a little until they fit together right. It wasn't a huge deal, though.