Help I am trying to source a plastic elbow connector from a sink drain hole. I broke the last one by over tightening a central screw in the plug hole. I have discovered that there is a central threaded column in the outlet pipe which allows it to be pulled tight underneath the plug hole by use of a central screw on the topside. Having had a quick look on the internet I can't seem to find such a product. Does this coupling have a specific name I could search for, or perhaps someone could suggest where I might purchase this item. Many thanks.