Haven't read all the posts, so apologies if this has already been suggested.
I had the same problems after getting a setup with identical connectors. It was becoming really frustrating trying to force the connections together.
In the end all it took was a simple bit of filing. Just gently file away the burred edge of the male connector and it will slot into place no trouble at all. I've done this with a couple of mine and they seem to be lasting forever now in comparison to before.
Hope this helps,
lance