The connector pins are a big PIA. To solve the problem I held one end in a needle nosed vise grip and increased the opening with a dremel tool, then swapped ends. Also bevel the edges on the opening at both ends to go on the rail easier.
The only thing I do not like about the shelving is the 3 rail. It is display shelving, two rail is sufficient. I have mentioned this to Glen, but to no avail.
bruce